From: Omar Polo <op@omarpolo.com>
Subject: Re: regress: change how trim_obj_id works
To: gameoftrees@openbsd.org
Date: Sat, 13 Jul 2024 16:09:24 +0200

Omar Polo <op@omarpolo.com> wrote:
> trim_obj_ids is a bit weird IMHO in that you have to specify how many
> characters to drop *from the end* instead of how many to keep from the
> beginning.  This comes in the way of enabling some parts of the regress
> for sha256 since object IDs are longer, and a `trim_obj_id 38` will not
> yield 2 characters, but 26!
> 
> Instead, what about using the numeric argument to mean the number of
> characters to keep from the beginning?  Then `trim_obj_id 2` will always
> return the first two characters, regardless of the length of the hash.
> 
> The diff boils down to
> 
> @@ -132,13 +132,7 @@ trim_obj_id()
>         local trimcount=$1
>         local id=$2
> 
> -       local pat=""
> -       while [ "$trimcount" -gt 0 ]; do
> -               pat="[0-9a-f]$pat"
> -               trimcount=$((trimcount - 1))
> -       done
> -
> -       echo ${id%$pat}
> +       echo "$id" | sed -E "s/^([0-9a-f]{$trimcount}).*/\1/"
>  }
> 
> plus a mechanical fix for all the places where it's used.  Regress of
> course passes.  ok?

forgot to stage a few files, here's a diff that fixes tog/ and gotd/
too.

commit b080979bc778860cf2c4648e7dd1b82ee0b7131e
from: Omar Polo <op@omarpolo.com>
date: Sat Jul 13 14:08:24 2024 UTC
 
 swap trim_obj_id behaviour
 
diff a96c0eca406fbbdec4a21b0fc2589bdbc9c0d04a b080979bc778860cf2c4648e7dd1b82ee0b7131e
commit - a96c0eca406fbbdec4a21b0fc2589bdbc9c0d04a
commit + b080979bc778860cf2c4648e7dd1b82ee0b7131e
blob - d60fc3d989f80b6803c66daddd2280f9ac6bee96
blob + d029636f37e1e06a4fba931a86782da565457b03
--- regress/cmdline/blame.sh
+++ regress/cmdline/blame.sh
@@ -61,9 +61,9 @@ test_blame_basic() {
 
 	(cd $testroot/wt && got blame alpha > $testroot/stdout)
 
-	local short_commit1=`trim_obj_id 32 $commit1`
-	local short_commit2=`trim_obj_id 32 $commit2`
-	local short_commit3=`trim_obj_id 32 $commit3`
+	local short_commit1=`trim_obj_id 8 $commit1`
+	local short_commit2=`trim_obj_id 8 $commit2`
+	local short_commit3=`trim_obj_id 8 $commit3`
 
 	d=`date -u -r $author_time +"%F"`
 	echo "1) $short_commit1 $d $GOT_AUTHOR_8 1" > $testroot/stdout.expected
@@ -110,8 +110,8 @@ test_blame_tag() {
 
 	(cd $testroot/wt && got blame -c $tag alpha > $testroot/stdout)
 
-	local short_commit1=`trim_obj_id 32 $commit1`
-	local short_commit2=`trim_obj_id 32 $commit2`
+	local short_commit1=`trim_obj_id 8 $commit1`
+	local short_commit2=`trim_obj_id 8 $commit2`
 
 	d=`date -u -r $author_time +"%F"`
 	echo "1) $short_commit1 $d $GOT_AUTHOR_8 1" > $testroot/stdout.expected
@@ -147,7 +147,7 @@ test_blame_file_single_line() {
 
 	(cd $testroot/wt && got blame alpha > $testroot/stdout)
 
-	local short_commit1=`trim_obj_id 32 $commit1`
+	local short_commit1=`trim_obj_id 8 $commit1`
 
 	d=`date -u -r $author_time +"%F"`
 	echo "1) $short_commit1 $d $GOT_AUTHOR_8 1" > $testroot/stdout.expected
@@ -182,7 +182,7 @@ test_blame_file_single_line_no_newline() {
 
 	(cd $testroot/wt && got blame alpha > $testroot/stdout)
 
-	local short_commit1=`trim_obj_id 32 $commit1`
+	local short_commit1=`trim_obj_id 8 $commit1`
 
 	d=`date -u -r $author_time +"%F"`
 	echo "1) $short_commit1 $d $GOT_AUTHOR_8 1" > $testroot/stdout.expected
@@ -208,7 +208,7 @@ test_blame_all_lines_replaced() {
 	seq 8 > $testroot/wt/alpha
 	(cd $testroot/wt && got commit -m "change 1" > /dev/null)
 	local commit1=`git_show_head $testroot/repo`
-	local short_commit1=`trim_obj_id 32 $commit1`
+	local short_commit1=`trim_obj_id 8 $commit1`
 	local author_time=`git_show_author_time $testroot/repo`
 
 	(cd $testroot/wt && got blame alpha > $testroot/stdout)
@@ -245,7 +245,7 @@ test_blame_lines_shifted_up() {
 	seq 8 > $testroot/wt/alpha
 	(cd $testroot/wt && got commit -m "change 1" > /dev/null)
 	local commit1=`git_show_head $testroot/repo`
-	local short_commit1=`trim_obj_id 32 $commit1`
+	local short_commit1=`trim_obj_id 8 $commit1`
 	local author_time=`git_show_author_time $testroot/repo`
 
 	ed -s $testroot/wt/alpha <<-\EOF
@@ -254,7 +254,7 @@ test_blame_lines_shifted_up() {
 	EOF
 	(cd $testroot/wt && got commit -m "change 2" > /dev/null)
 	local commit2=`git_show_head $testroot/repo`
-	local short_commit2=`trim_obj_id 32 $commit2`
+	local short_commit2=`trim_obj_id 8 $commit2`
 
 	seq 2 > $testroot/wt/alpha
 	echo foo >> $testroot/wt/alpha
@@ -263,7 +263,7 @@ test_blame_lines_shifted_up() {
 	seq 6 8 >> $testroot/wt/alpha
 	(cd $testroot/wt && got commit -m "change 3" > /dev/null)
 	local commit3=`git_show_head $testroot/repo`
-	local short_commit3=`trim_obj_id 32 $commit3`
+	local short_commit3=`trim_obj_id 8 $commit3`
 	local author_time=`git_show_author_time $testroot/repo`
 
 	(cd $testroot/wt && got blame alpha > $testroot/stdout)
@@ -304,7 +304,7 @@ test_blame_lines_shifted_down() {
 	seq 8 > $testroot/wt/alpha
 	(cd $testroot/wt && got commit -m "change 1" > /dev/null)
 	local commit1=`git_show_head $testroot/repo`
-	local short_commit1=`trim_obj_id 32 $commit1`
+	local short_commit1=`trim_obj_id 8 $commit1`
 	local author_time=`git_show_author_time $testroot/repo`
 
 	ed -s $testroot/wt/alpha <<-\EOF
@@ -313,7 +313,7 @@ test_blame_lines_shifted_down() {
 	EOF
 	(cd $testroot/wt && got commit -m "change 2" > /dev/null)
 	local commit2=`git_show_head $testroot/repo`
-	local short_commit2=`trim_obj_id 32 $commit2`
+	local short_commit2=`trim_obj_id 8 $commit2`
 
 	seq 2 > $testroot/wt/alpha
 	echo foo >> $testroot/wt/alpha
@@ -322,7 +322,7 @@ test_blame_lines_shifted_down() {
 	seq 3 8 >> $testroot/wt/alpha
 	(cd $testroot/wt && got commit -m "change 3" > /dev/null)
 	local commit3=`git_show_head $testroot/repo`
-	local short_commit3=`trim_obj_id 32 $commit3`
+	local short_commit3=`trim_obj_id 8 $commit3`
 	local author_time=`git_show_author_time $testroot/repo`
 
 	(cd $testroot/wt && got blame alpha > $testroot/stdout)
@@ -398,7 +398,7 @@ dvi: # do nothing to build dvi
 EOF
 	(cd $testroot/wt && got commit -m "change 1" > /dev/null)
 	local commit1=`git_show_head $testroot/repo`
-	local short_commit1=`trim_obj_id 32 $commit1`
+	local short_commit1=`trim_obj_id 8 $commit1`
 	local author_time1=`git_show_author_time $testroot/repo`
 	local d1=`date -u -r $author_time1 +"%F"`
 
@@ -425,7 +425,7 @@ EOF
 	# all changes in this commit will be subsumed by later commits
 	(cd $testroot/wt && got commit -m "change 2" > /dev/null)
 	local commit2=`git_show_head $testroot/repo`
-	local short_commit2=`trim_obj_id 32 $commit2`
+	local short_commit2=`trim_obj_id 8 $commit2`
 	local author_time2=`git_show_author_time $testroot/repo`
 	local d2=`date -u -r $author_time2 +"%F"`
 
@@ -449,7 +449,7 @@ dvi: # do nothing to build dvi
 EOF
 	(cd $testroot/wt && got commit -m "change 3" > /dev/null)
 	local commit3=`git_show_head $testroot/repo`
-	local short_commit3=`trim_obj_id 32 $commit3`
+	local short_commit3=`trim_obj_id 8 $commit3`
 	local author_time3=`git_show_author_time $testroot/repo`
 	local d3=`date -u -r $author_time3 +"%F"`
 
@@ -473,7 +473,7 @@ dvi: # do nothing to build dvi
 EOF
 	(cd $testroot/wt && got commit -m "change 4" > /dev/null)
 	local commit4=`git_show_head $testroot/repo`
-	local short_commit4=`trim_obj_id 32 $commit4`
+	local short_commit4=`trim_obj_id 8 $commit4`
 	local author_time4=`git_show_author_time $testroot/repo`
 	local d4=`date -u -r $author_time4 +"%F"`
 
@@ -720,9 +720,9 @@ test_blame_added_on_branch() {
 
 	(cd $testroot/wt && got blame new > $testroot/stdout)
 
-	local short_commit1=`trim_obj_id 32 $commit1`
-	local short_commit2=`trim_obj_id 32 $commit2`
-	local short_commit3=`trim_obj_id 32 $commit3`
+	local short_commit1=`trim_obj_id 8 $commit1`
+	local short_commit2=`trim_obj_id 8 $commit2`
+	local short_commit3=`trim_obj_id 8 $commit3`
 
 	d=`date -u -r $author_time +"%F"`
 	echo "1) $short_commit1 $d $GOT_AUTHOR_8 1" > $testroot/stdout.expected
@@ -772,7 +772,7 @@ test_blame_submodule() {
 test_blame_symlink() {
 	local testroot=`test_init blame_symlink`
 	local commit_id0=`git_show_head $testroot/repo`
-	local short_commit0=`trim_obj_id 32 $commit_id0`
+	local short_commit0=`trim_obj_id 8 $commit_id0`
 
 	(cd $testroot/repo && ln -s alpha alpha.link)
 	(cd $testroot/repo && ln -s epsilon epsilon.link)
@@ -783,7 +783,7 @@ test_blame_symlink() {
 	git_commit $testroot/repo -m "add symlinks"
 
 	local commit_id1=`git_show_head $testroot/repo`
-	local short_commit1=`trim_obj_id 32 $commit_id1`
+	local short_commit1=`trim_obj_id 8 $commit_id1`
 	local author_time=`git_show_author_time $testroot/repo`
 
 	# got blame dereferences symlink to a regular file
@@ -907,7 +907,7 @@ D
 EOF
 	(cd $testroot/wt && got commit -m "change 1" > /dev/null)
 	local commit1=`git_show_head $testroot/repo`
-	local short_commit1=`trim_obj_id 32 $commit1`
+	local short_commit1=`trim_obj_id 8 $commit1`
 	local author_time1=`git_show_author_time $testroot/repo`
 
 	cat > $testroot/wt/alpha <<EOF
@@ -920,7 +920,7 @@ Q
 EOF
 	(cd $testroot/wt && got commit -m "change 2" > /dev/null)
 	local commit2=`git_show_head $testroot/repo`
-	local short_commit2=`trim_obj_id 32 $commit2`
+	local short_commit2=`trim_obj_id 8 $commit2`
 	local author_time2=`git_show_author_time $testroot/repo`
 
 	cat > $testroot/wt/alpha <<EOF
@@ -934,7 +934,7 @@ Q
 EOF
 	(cd $testroot/wt && got commit -m "change 3" > /dev/null)
 	local commit3=`git_show_head $testroot/repo`
-	local short_commit3=`trim_obj_id 32 $commit3`
+	local short_commit3=`trim_obj_id 8 $commit3`
 	local author_time3=`git_show_author_time $testroot/repo`
 
 	cat > $testroot/wt/alpha <<EOF
@@ -947,7 +947,7 @@ Q
 EOF
 	(cd $testroot/wt && got commit -m "change 4" > /dev/null)
 	local commit4=`git_show_head $testroot/repo`
-	local short_commit4=`trim_obj_id 32 $commit4`
+	local short_commit4=`trim_obj_id 8 $commit4`
 	local author_time4=`git_show_author_time $testroot/repo`
 
 	cat > $testroot/wt/alpha <<EOF
@@ -961,7 +961,7 @@ Q
 EOF
 	(cd $testroot/wt && got commit -m "change 5" > /dev/null)
 	local commit5=`git_show_head $testroot/repo`
-	local short_commit5=`trim_obj_id 32 $commit5`
+	local short_commit5=`trim_obj_id 8 $commit5`
 	local author_time5=`git_show_author_time $testroot/repo`
 
 	(cd $testroot/wt && got blame alpha > $testroot/stdout)
@@ -997,7 +997,7 @@ test_blame_commit_keywords() {
 	local wt="$testroot/wt"
 	local id=$(git_show_head "$repo")
 
-	set -- "$(trim_obj_id 32 $id)"
+	set -- "$(trim_obj_id 8 $id)"
 
 	# :base requires work tree
 	echo "got: '-c :base' requires work tree" > "$testroot/stderr.expected"
@@ -1038,7 +1038,7 @@ test_blame_commit_keywords() {
 		fi
 
 		id=$(git_show_head "$repo")
-		set -- "$@" "$(trim_obj_id 32 $id)"
+		set -- "$@" "$(trim_obj_id 8 $id)"
 	done
 
 	local author_time=$(git_show_author_time "$repo")
blob - fa88b8e9da3292f78931b60f217cfd5ede722f86
blob + a43ed7a5edf97dd118bdc839444f242a3b12dbe4
--- regress/cmdline/common.sh
+++ regress/cmdline/common.sh
@@ -132,13 +132,7 @@ trim_obj_id()
 	local trimcount=$1
 	local id=$2
 
-	local pat=""
-	while [ "$trimcount" -gt 0 ]; do
-		pat="[0-9a-f]$pat"
-		trimcount=$((trimcount - 1))
-	done
-
-	echo ${id%$pat}
+	echo "$id" | sed -E "s/^([0-9a-f]{$trimcount}).*/\1/"
 }
 
 pop_idx()
@@ -201,7 +195,7 @@ get_loose_object_path()
 {
 	local repo="$1"
 	local id="$2"
-	local id0=`trim_obj_id 38 $id`
+	local id0=`trim_obj_id 2 $id`
 	local idrest=`echo ${id#[0-9a-f][0-9a-f]}`
 	echo "$repo/.git/objects/$id0/$idrest"
 }
blob - 758167f8b5e07885c9944d76d57660a8d0a7afc1
blob + c7454905559296ba3c95edb66a8cf17f0700d11a
--- regress/cmdline/histedit.sh
+++ regress/cmdline/histedit.sh
@@ -55,10 +55,10 @@ test_histedit_no_op() {
 	local new_commit2=`git_show_head $testroot/repo`
 	local new_author_time2=`git_show_author_time $testroot/repo`
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "G  alpha" > $testroot/stdout.expected
 	echo "D  beta" >> $testroot/stdout.expected
@@ -267,10 +267,10 @@ test_histedit_swap() {
 	local new_commit2=`git_show_parent_commit $testroot/repo`
 	local new_commit1=`git_show_head $testroot/repo`
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "G  epsilon/zeta" > $testroot/stdout.expected
 	echo -n "$short_old_commit2 -> $short_new_commit2: " \
@@ -388,9 +388,9 @@ test_histedit_drop() {
 
 	local new_commit2=`git_show_head $testroot/repo`
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "$short_old_commit1 ->  drop commit: committing changes" \
 		> $testroot/stdout.expected
@@ -511,11 +511,11 @@ EOF
 	local new_commit1=`git_show_parent_commit $testroot/repo`
 	local new_commit2=`git_show_head $testroot/repo`
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
-	local short_old_commit3=`trim_obj_id 28 $old_commit3`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
+	local short_old_commit3=`trim_obj_id 12 $old_commit3`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "G  alpha" > $testroot/stdout.expected
 	echo "D  beta" >> $testroot/stdout.expected
@@ -617,8 +617,8 @@ test_histedit_edit() {
 	(cd $testroot/wt && got histedit -F $testroot/histedit-script \
 		> $testroot/stdout)
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
 
 	echo "G  alpha" > $testroot/stdout.expected
 	echo "D  beta" >> $testroot/stdout.expected
@@ -675,8 +675,8 @@ EOF
 	local new_commit1=`git_show_parent_commit $testroot/repo`
 	local new_commit2=`git_show_head $testroot/repo`
 
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "$short_old_commit1 -> $short_new_commit1: committing changes" \
 		> $testroot/stdout.expected
@@ -926,8 +926,8 @@ test_histedit_abort() {
 	(cd $testroot/wt && got histedit -F $testroot/histedit-script \
 		> $testroot/stdout)
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
 
 	echo "G  alpha" > $testroot/stdout.expected
 	echo "D  beta" >> $testroot/stdout.expected
@@ -1058,8 +1058,8 @@ test_histedit_path_prefix_drop() {
 	(cd $testroot/wt && got histedit -F $testroot/histedit-script \
 		> $testroot/stdout)
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
 
 	echo "$short_old_commit1 ->  drop commit: changing zeta" \
 		> $testroot/stdout.expected
@@ -1161,7 +1161,7 @@ test_histedit_path_prefix_edit() {
 	(cd $testroot/wt && got histedit -F $testroot/histedit-script \
 		> $testroot/stdout)
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
 
 	echo "G  zeta" > $testroot/stdout.expected
 	echo "Stopping histedit for amending commit $old_commit1" \
@@ -1212,7 +1212,7 @@ EOF
 		got histedit -c > $testroot/stdout)
 
 	local new_commit1=`git_show_head $testroot/repo`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
 
 	echo -n "$short_old_commit1 -> $short_new_commit1: " \
 		> $testroot/stdout.expected
@@ -1359,9 +1359,9 @@ EOF
 
 	local new_commit=`git_show_head $testroot/repo`
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
-	local short_new_commit=`trim_obj_id 28 $new_commit`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
+	local short_new_commit=`trim_obj_id 12 $new_commit`
 
 	echo "G  epsilon/zeta" >> $testroot/stdout.expected
 	echo -n "$short_old_commit2 ->  fold commit: committing to zeta " \
@@ -1395,12 +1395,12 @@ test_histedit_split_commit() {
 	git -C $testroot/repo add epsilon/new
 	git_commit $testroot/repo -m "committing changes 1"
 	local old_commit1=`git_show_head $testroot/repo`
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
 
 	echo "modified zeta on master" > $testroot/repo/epsilon/zeta
 	git_commit $testroot/repo -m "committing changes 2"
 	local old_commit2=`git_show_head $testroot/repo`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
 
 	got checkout -c $orig_commit $testroot/repo $testroot/wt > /dev/null
 	ret=$?
@@ -1471,7 +1471,7 @@ test_histedit_split_commit() {
 		return 1
 	fi
 	local new_commit2=`git_show_head $testroot/repo`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "$short_old_commit1 -> no-op change: committing changes 1" \
 		> $testroot/stdout.expected
@@ -1587,10 +1587,10 @@ EOF
 
 	local new_commit1=`git_show_head $testroot/repo`
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
-	local short_old_commit3=`trim_obj_id 28 $old_commit3`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
+	local short_old_commit3=`trim_obj_id 12 $old_commit3`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
 
 	echo "A  epsilon/psi" >> $testroot/stdout.expected
 	echo "$short_old_commit1 ->  fold commit: committing changes" \
@@ -1690,9 +1690,9 @@ EOF
 
 	local new_commit1=`git_show_head $testroot/repo`
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
 
 	echo "G  alpha" >> $testroot/stdout.expected
 	echo "$short_old_commit1 ->  fold commit: modified alpha" \
@@ -1779,9 +1779,9 @@ EOF
 
 	local new_commit1=`git_show_head $testroot/repo`
 	
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
 
 	echo "D  alpha" > $testroot/stdout.expected
 	echo "$short_old_commit1 ->  fold commit: removing alpha" \
@@ -1859,11 +1859,11 @@ EOF
 
 	local new_commit1=`git_show_head $testroot/repo`
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
-	local short_old_commit3=`trim_obj_id 28 $old_commit3`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
+	local short_old_commit3=`trim_obj_id 12 $old_commit3`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "G  alpha" > $testroot/stdout.expected
 	echo "D  beta" >> $testroot/stdout.expected
@@ -1978,12 +1978,12 @@ EOF
 
 	local new_commit1=`git_show_head $testroot/repo`
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local very_short_old_commit1=`trim_obj_id 29 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
-	local short_old_commit3=`trim_obj_id 28 $old_commit3`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local very_short_old_commit1=`trim_obj_id 11 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
+	local short_old_commit3=`trim_obj_id 12 $old_commit3`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "G  alpha" > $testroot/stdout.expected
 	echo "D  beta" >> $testroot/stdout.expected
@@ -2083,8 +2083,8 @@ test_histedit_edit_only() {
 
 	(cd $testroot/wt && got histedit -e > $testroot/stdout)
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
 
 	echo "G  alpha" > $testroot/stdout.expected
 	echo "D  beta" >> $testroot/stdout.expected
@@ -2115,7 +2115,7 @@ EOF
 
 	local new_commit1=$(cd $testroot/wt && got info | \
 		grep '^work tree base commit: ' | cut -d: -f2 | tr -d ' ')
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
 
 	echo -n "$short_old_commit1 -> $short_new_commit1: " \
 		> $testroot/stdout.expected
@@ -2146,7 +2146,7 @@ EOF
 		VISUAL="$testroot/editor.sh" got histedit -c > $testroot/stdout)
 
 	local new_commit2=`git_show_head $testroot/repo`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo -n "$short_old_commit2 -> $short_new_commit2: " \
 		> $testroot/stdout.expected
@@ -2437,8 +2437,8 @@ EOF
 	local new_commit1=`git_show_head $testroot/repo`
 	local new_author_time1=`git_show_author_time $testroot/repo`
 
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
 
 	echo "G  alpha" > $testroot/stdout.expected
 	echo "$short_old_commit1 -> $short_new_commit1: set executable bit on alpha" \
@@ -2530,9 +2530,9 @@ test_histedit_drop_only() {
 	(cd $testroot/wt && got histedit -d > $testroot/stdout)
 	local new_commit1=`git_show_head $testroot/repo`
 
-	local short_commit1=`trim_obj_id 28 $drop_commit1`
-	local short_commit2=`trim_obj_id 28 $drop_commit2`
-	local short_commit3=`trim_obj_id 28 $drop_commit3`
+	local short_commit1=`trim_obj_id 12 $drop_commit1`
+	local short_commit2=`trim_obj_id 12 $drop_commit2`
+	local short_commit3=`trim_obj_id 12 $drop_commit3`
 
 	echo "$short_commit1 $drop $dropmsg 1" > $testroot/stdout.expected
 	echo "$short_commit2 $drop $dropmsg 2" >> $testroot/stdout.expected
@@ -2618,17 +2618,17 @@ test_histedit_conflict_revert() {
 	echo "first change of alpha" > $testroot/repo/alpha
 	git_commit $testroot/repo -m "committing changes"
 	local old_commit1=`git_show_head $testroot/repo`
-	local short_old_commit1=`trim_obj_id 28 $old_commit1`
+	local short_old_commit1=`trim_obj_id 12 $old_commit1`
 
 	echo "second change of alpha" > $testroot/repo/alpha
 	git_commit $testroot/repo -m "committing changes"
 	local old_commit2=`git_show_head $testroot/repo`
-	local short_old_commit2=`trim_obj_id 28 $old_commit2`
+	local short_old_commit2=`trim_obj_id 12 $old_commit2`
 
 	echo "third change of alpha" > $testroot/repo/alpha
 	git_commit $testroot/repo -m "committing changes"
 	local old_commit3=`git_show_head $testroot/repo`
-	local short_old_commit3=`trim_obj_id 28 $old_commit3`
+	local short_old_commit3=`trim_obj_id 12 $old_commit3`
 
 	got checkout -c $orig_commit $testroot/repo $testroot/wt > /dev/null
 	ret=$?
@@ -2672,7 +2672,7 @@ EOF
 
 	local new_commit1=$(cd $testroot/wt && got info | \
 		grep 'work tree base commit:' | cut -d ' ' -f5)
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
 
 	echo "$short_old_commit1 -> $short_new_commit1: committing changes" \
 		> $testroot/stdout.expected
blob - d8eb96bab4f0e3966cb1fb48167fcf1be88c38f7
blob + b1c3c8ec3866e7ac66371da08256f2fa1212a13c
--- regress/cmdline/log.sh
+++ regress/cmdline/log.sh
@@ -1275,10 +1275,10 @@ test_log_toposort() {
 	local merge_commit=`git_show_head $testroot/repo`
 	local merge_time=`git_show_author_time $testroot/repo`
 
-	local short_commit0=`trim_obj_id 33 $commit0`
-	local short_commit1=`trim_obj_id 33 $commit1`
-	local short_commit2=`trim_obj_id 33 $commit2`
-	local short_commit3=`trim_obj_id 33 $commit3`
+	local short_commit0=`trim_obj_id 7 $commit0`
+	local short_commit1=`trim_obj_id 7 $commit1`
+	local short_commit2=`trim_obj_id 7 $commit2`
+	local short_commit3=`trim_obj_id 7 $commit3`
 
 	d_0=`date -u -r $author_time0 +"%F"`
 	d_1=`date -u -r $author_time1 +"%F"`
blob - fdc97d042d96cc880bf32dab15045285d6a80e27
blob + c824aaf0100a26fa4d112f62f5136272c5c82bbc
--- regress/cmdline/rebase.sh
+++ regress/cmdline/rebase.sh
@@ -67,10 +67,10 @@ test_rebase_basic() {
 	local new_commit2=`git_show_head $testroot/repo`
 	local new_author_time2=`git_show_author_time $testroot/repo`
 
-	local short_orig_commit1=`trim_obj_id 28 $orig_commit1`
-	local short_orig_commit2=`trim_obj_id 28 $orig_commit2`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_orig_commit1=`trim_obj_id 12 $orig_commit1`
+	local short_orig_commit2=`trim_obj_id 12 $orig_commit2`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "G  gamma/delta" >> $testroot/stdout.expected
 	echo -n "$short_orig_commit1 -> $short_new_commit1" \
@@ -293,7 +293,7 @@ test_rebase_continue() {
 	echo "modified alpha on branch" > $testroot/repo/alpha
 	git_commit $testroot/repo -m "committing to alpha on newbranch"
 	local orig_commit1=`git_show_head $testroot/repo`
-	local short_orig_commit1=`trim_obj_id 28 $orig_commit1`
+	local short_orig_commit1=`trim_obj_id 12 $orig_commit1`
 
 	git -C $testroot/repo checkout -q master
 	echo "modified alpha on master" > $testroot/repo/alpha
@@ -395,7 +395,7 @@ EOF
 
 	git -C $testroot/repo checkout -q newbranch
 	local new_commit1=`git_show_head $testroot/repo`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
 
 	echo -n "$short_orig_commit1 -> $short_new_commit1" \
 		> $testroot/stdout.expected
@@ -432,7 +432,7 @@ test_rebase_abort() {
 	echo "modified beta on branch" > $testroot/repo/beta
 	git_commit $testroot/repo -m "committing to beta on newbranch"
 	local orig_commit1=`git_show_head $testroot/repo`
-	local short_orig_commit1=`trim_obj_id 28 $orig_commit1`
+	local short_orig_commit1=`trim_obj_id 12 $orig_commit1`
 
 	echo "modified alpha on branch" > $testroot/repo/alpha
 	echo "new file on branch" > $testroot/repo/epsilon/new
@@ -440,7 +440,7 @@ test_rebase_abort() {
 	git_commit $testroot/repo \
 		-m "changing alpha and adding new on newbranch"
 	local orig_commit2=`git_show_head $testroot/repo`
-	local short_orig_commit2=`trim_obj_id 28 $orig_commit2`
+	local short_orig_commit2=`trim_obj_id 12 $orig_commit2`
 
 	git -C $testroot/repo checkout -q master
 	echo "modified alpha on master" > $testroot/repo/alpha
@@ -462,7 +462,7 @@ test_rebase_abort() {
 
 	new_commit1=$(cd $testroot/wt && got info beta | \
 		grep '^based on commit:' | cut -d' ' -f4)
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
 	
 	echo "G  beta" > $testroot/stdout.expected
 	echo -n "$short_orig_commit1 -> $short_new_commit1" \
@@ -628,7 +628,7 @@ test_rebase_no_op_change() {
 	echo "modified alpha on branch" > $testroot/repo/alpha
 	git_commit $testroot/repo -m "committing to alpha on newbranch"
 	local orig_commit1=`git_show_head $testroot/repo`
-	local short_orig_commit1=`trim_obj_id 28 $orig_commit1`
+	local short_orig_commit1=`trim_obj_id 12 $orig_commit1`
 
 	git -C $testroot/repo checkout -q master
 	echo "modified alpha on master" > $testroot/repo/alpha
@@ -743,7 +743,7 @@ test_rebase_in_progress() {
 	echo "modified alpha on branch" > $testroot/repo/alpha
 	git_commit $testroot/repo -m "committing to alpha on newbranch"
 	local orig_commit1=`git_show_head $testroot/repo`
-	local short_orig_commit1=`trim_obj_id 28 $orig_commit1`
+	local short_orig_commit1=`trim_obj_id 12 $orig_commit1`
 
 	git -C $testroot/repo checkout -q master
 	echo "modified alpha on master" > $testroot/repo/alpha
@@ -904,8 +904,8 @@ test_rebase_path_prefix() {
 	local new_commit1=`git_show_parent_commit $testroot/repo`
 	local new_commit2=`git_show_head $testroot/repo`
 
-	local short_orig_commit2=`trim_obj_id 28 $orig_commit2`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_orig_commit2=`trim_obj_id 12 $orig_commit2`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "G  gamma/delta" > $testroot/stdout.expected
 	echo -n "$short_orig_commit2 -> $short_new_commit2" \
@@ -1364,10 +1364,10 @@ test_rebase_trims_empty_dir() {
 	local new_commit1=`git_show_parent_commit $testroot/repo`
 	local new_commit2=`git_show_head $testroot/repo`
 
-	local short_orig_commit1=`trim_obj_id 28 $orig_commit1`
-	local short_orig_commit2=`trim_obj_id 28 $orig_commit2`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_orig_commit1=`trim_obj_id 12 $orig_commit1`
+	local short_orig_commit2=`trim_obj_id 12 $orig_commit2`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "G  gamma/delta" >> $testroot/stdout.expected
 	echo -n "$short_orig_commit1 -> $short_new_commit1" \
@@ -1463,8 +1463,8 @@ test_rebase_delete_missing_file() {
 	local orig_commit1=`git_show_parent_commit $testroot/repo`
 	local orig_commit2=`git_show_head $testroot/repo`
 
-	local short_orig_commit1=`trim_obj_id 28 $orig_commit1`
-	local short_orig_commit2=`trim_obj_id 28 $orig_commit2`
+	local short_orig_commit1=`trim_obj_id 12 $orig_commit1`
+	local short_orig_commit2=`trim_obj_id 12 $orig_commit2`
 
 	(cd $testroot/wt && got update -b master > /dev/null)
 	(cd $testroot/wt && got rm beta d/f/g/new > /dev/null)
@@ -1487,8 +1487,8 @@ test_rebase_delete_missing_file() {
 	local new_commit1=$(cd $testroot/wt && got info | \
 		grep '^work tree base commit: ' | cut -d: -f2 | tr -d ' ')
 
-	local short_orig_commit2=`trim_obj_id 28 $orig_commit2`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
+	local short_orig_commit2=`trim_obj_id 12 $orig_commit2`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
 
 	echo "G  gamma/delta" >> $testroot/stdout.expected
 	echo -n "$short_orig_commit1 -> $short_new_commit1" \
@@ -1572,7 +1572,7 @@ test_rebase_delete_missing_file() {
 
 	git -C $testroot/repo checkout -q newbranch
 	local new_commit1=`git_show_head $testroot/repo`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
 
 	(cd $testroot/wt && got log -l3 | grep ^commit > $testroot/stdout)
 	echo "commit $new_commit1 (newbranch)" > $testroot/stdout.expected
@@ -1633,12 +1633,12 @@ test_rebase_rm_add_rm_file() {
 
 	git -C $testroot/repo checkout -q newbranch
 
-	local short_orig_commit1=`trim_obj_id 28 $orig_commit1`
-	local short_orig_commit2=`trim_obj_id 28 $orig_commit2`
-	local short_orig_commit3=`trim_obj_id 28 $orig_commit3`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
-	local short_new_commit3=`trim_obj_id 28 $new_commit3`
+	local short_orig_commit1=`trim_obj_id 12 $orig_commit1`
+	local short_orig_commit2=`trim_obj_id 12 $orig_commit2`
+	local short_orig_commit3=`trim_obj_id 12 $orig_commit3`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
+	local short_new_commit3=`trim_obj_id 12 $new_commit3`
 
 	echo "D  beta" > $testroot/stdout.expected
 	echo -n "$short_orig_commit1 -> $short_new_commit1" \
@@ -1730,10 +1730,10 @@ test_rebase_resets_committer() {
 	local new_commit2=`git_show_head $testroot/repo`
 	local new_author_time2=`git_show_author_time $testroot/repo`
 
-	local short_orig_commit1=`trim_obj_id 28 $orig_commit1`
-	local short_orig_commit2=`trim_obj_id 28 $orig_commit2`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_orig_commit1=`trim_obj_id 12 $orig_commit1`
+	local short_orig_commit2=`trim_obj_id 12 $orig_commit2`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "G  gamma/delta" >> $testroot/stdout.expected
 	echo -n "$short_orig_commit1 -> $short_new_commit1" \
@@ -1819,10 +1819,10 @@ test_rebase_no_author_info() {
 	local new_commit2=`git_show_head $testroot/repo`
 	local new_author_time2=`git_show_author_time $testroot/repo`
 
-	local short_orig_commit1=`trim_obj_id 28 $orig_commit1`
-	local short_orig_commit2=`trim_obj_id 28 $orig_commit2`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
-	local short_new_commit2=`trim_obj_id 28 $new_commit2`
+	local short_orig_commit1=`trim_obj_id 12 $orig_commit1`
+	local short_orig_commit2=`trim_obj_id 12 $orig_commit2`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
+	local short_new_commit2=`trim_obj_id 12 $new_commit2`
 
 	echo "G  gamma/delta" >> $testroot/stdout.expected
 	echo -n "$short_orig_commit1 -> $short_new_commit1" \
@@ -2096,16 +2096,16 @@ test_rebase_merge_commit() {
 	(cd $testroot/wt && got rebase newbranch2) > $testroot/stdout
 
 	local new_commit5=`git_show_parent_commit $testroot/repo newbranch2`
-	local short_orig_commit5=`trim_obj_id 28 $commit5`
-	local short_new_commit5=`trim_obj_id 28 $new_commit5`
+	local short_orig_commit5=`trim_obj_id 12 $commit5`
+	local short_new_commit5=`trim_obj_id 12 $new_commit5`
 
 	local new_commit4=`git_show_parent_commit $testroot/repo $new_commit5`
-	local short_orig_commit4=`trim_obj_id 28 $commit4`
-	local short_new_commit4=`trim_obj_id 28 $new_commit4`
+	local short_orig_commit4=`trim_obj_id 12 $commit4`
+	local short_new_commit4=`trim_obj_id 12 $new_commit4`
 
 	local new_merge_commit=`git_show_branch_head $testroot/repo newbranch2`
-	local short_orig_merge_commit=`trim_obj_id 28 $merge_commit`
-	local short_new_merge_commit=`trim_obj_id 28 $new_merge_commit`
+	local short_orig_merge_commit=`trim_obj_id 12 $merge_commit`
+	local short_new_merge_commit=`trim_obj_id 12 $new_merge_commit`
 
 	echo "G  beta"> $testroot/stdout.expected
 	echo "$short_orig_commit4 -> $short_new_commit4: edit beta" \
@@ -2193,8 +2193,8 @@ test_rebase_across_merge_commit() {
 	(cd $testroot/wt && got rebase master) > $testroot/stdout
 
 	local new_commit1=`git_show_head $testroot/repo`
-	local short_orig_commit1=`trim_obj_id 28 $commit1`
-	local short_new_commit1=`trim_obj_id 28 $new_commit1`
+	local short_orig_commit1=`trim_obj_id 12 $commit1`
+	local short_new_commit1=`trim_obj_id 12 $new_commit1`
 
 	echo "G  gamma/delta"> $testroot/stdout.expected
 	echo "$short_orig_commit1 -> $short_new_commit1: edit delta" \
blob - 87b2d0ee33cba60718822df7626b15b93e0b09ba
blob + 74a0bac7ae7cce3410954539245f192f58869070
--- regress/gotd/email_notification.sh
+++ regress/gotd/email_notification.sh
@@ -56,7 +56,7 @@ test_file_changed() {
 
 	wait %1 # wait for nc -l
 
-	short_commit_id=`trim_obj_id 28 $commit_id`
+	short_commit_id=`trim_obj_id 12 $commit_id`
 	HOSTNAME=`hostname`
 	printf "HELO localhost\r\n" > $testroot/stdout.expected
 	printf "MAIL FROM:<${GOTD_USER}@${HOSTNAME}>\r\n" \
@@ -138,7 +138,7 @@ test_many_commits_not_summarized() {
 
 	wait %1 # wait for nc -l
 
-	short_commit_id=`trim_obj_id 28 $commit_id`
+	short_commit_id=`trim_obj_id 12 $commit_id`
 	HOSTNAME=`hostname`
 	printf "HELO localhost\r\n" > $testroot/stdout.expected
 	printf "MAIL FROM:<${GOTD_USER}@${HOSTNAME}>\r\n" \
@@ -206,7 +206,7 @@ test_many_commits_summarized() {
 		echo "alpha $i" > $testroot/wt/alpha
 		(cd $testroot/wt && got commit -m 'make changes' > /dev/null)
 		local commit_id=`git_show_head $testroot/repo-clone`
-		local short_commit_id=`trim_obj_id 33 $commit_id`
+		local short_commit_id=`trim_obj_id 7 $commit_id`
 		local author_time=`git_show_author_time $testroot/repo-clone`
 		d=`date -u -r $author_time +"%F"`
 		set -- "$@" "$short_commit_id $d"
@@ -227,7 +227,7 @@ test_many_commits_summarized() {
 
 	wait %1 # wait for nc -l
 
-	short_commit_id=`trim_obj_id 28 $commit_id`
+	short_commit_id=`trim_obj_id 12 $commit_id`
 	HOSTNAME=`hostname`
 	printf "HELO localhost\r\n" > $testroot/stdout.expected
 	printf "MAIL FROM:<${GOTD_USER}@${HOSTNAME}>\r\n" \
@@ -305,7 +305,7 @@ test_branch_created() {
 
 	wait %1 # wait for nc -l
 
-	short_commit_id=`trim_obj_id 28 $commit_id`
+	short_commit_id=`trim_obj_id 12 $commit_id`
 	HOSTNAME=`hostname`
 	printf "HELO localhost\r\n" > $testroot/stdout.expected
 	printf "MAIL FROM:<${GOTD_USER}@${HOSTNAME}>\r\n" \
@@ -361,7 +361,7 @@ test_branch_removed() {
 	sleep 1 # server starts up
 
 	local commit_id=`git_show_branch_head $testroot/repo-clone newbranch`
-	local short_commit_id=`trim_obj_id 28 $commit_id`
+	local short_commit_id=`trim_obj_id 12 $commit_id`
 
 	got send -d newbranch -q -r $testroot/repo-clone
 	ret=$?
@@ -419,7 +419,7 @@ test_tag_created() {
 	local tagger_time=`git_show_tagger_time $testroot/repo-clone 1.0`
 	local tag_id=`got ref -r $testroot/repo-clone -l \
 		| grep "^refs/tags/$tag" | tr -d ' ' | cut -d: -f2`
-	local short_tag_id=`trim_obj_id 28 $tag_id`
+	local short_tag_id=`trim_obj_id 12 $tag_id`
 
 	(printf "220\r\n250\r\n250\r\n250\r\n354\r\n250\r\n221\r\n" \
 		| timeout 5 nc -l "$GOTD_TEST_SMTP_PORT" > $testroot/stdout) &
@@ -500,7 +500,7 @@ test_tag_changed() {
 	local tagger_time=`git_show_tagger_time $testroot/repo-clone 1.0`
 	local tag_id=`got ref -r $testroot/repo-clone -l \
 		| grep "^refs/tags/$tag" | tr -d ' ' | cut -d: -f2`
-	local short_tag_id=`trim_obj_id 28 $tag_id`
+	local short_tag_id=`trim_obj_id 12 $tag_id`
 
 	(printf "220\r\n250\r\n250\r\n250\r\n354\r\n250\r\n221\r\n" \
 		| timeout 5 nc -l "$GOTD_TEST_SMTP_PORT" > $testroot/stdout) &
blob - d3b27ff7a41130bee6fe4caab834d5f8a3f31319
blob + a358917969feee72a0c5245f6bcfb0062556fe9d
--- regress/gotd/http_notification.sh
+++ regress/gotd/http_notification.sh
@@ -403,7 +403,7 @@ test_many_commits_summarized() {
 		echo "alpha $i" > $testroot/wt/alpha
 		(cd $testroot/wt && got commit -m 'make changes' > /dev/null)
 		local commit_id=`git_show_head $testroot/repo-clone`
-		local short_commit_id=`trim_obj_id 33 $commit_id`
+		local short_commit_id=`trim_obj_id 7 $commit_id`
 		local author_time=`git_show_author_time $testroot/repo-clone`
 		set -- "$@" "$short_commit_id $author_time"
 	done
blob - 2a1df1daa4d10bc1df74a5b3e633844cb71a60eb
blob + 359a2b83b449269ee09d493e39bd5831e042b621
--- regress/tog/blame.sh
+++ regress/tog/blame.sh
@@ -48,10 +48,10 @@ WAIT_FOR_UI	wait for blame to finish
 SCREENDUMP
 EOF
 
-	local commit_id1_short=`trim_obj_id 32 $commit_id1`
-	local commit_id2_short=`trim_obj_id 32 $commit_id2`
-	local commit_id3_short=`trim_obj_id 32 $commit_id3`
-	local commit_id4_short=`trim_obj_id 32 $commit_id4`
+	local commit_id1_short=`trim_obj_id 8 $commit_id1`
+	local commit_id2_short=`trim_obj_id 8 $commit_id2`
+	local commit_id3_short=`trim_obj_id 8 $commit_id3`
+	local commit_id4_short=`trim_obj_id 8 $commit_id4`
 
 	cat <<EOF >$testroot/view.expected
 commit $commit_id4
@@ -114,7 +114,7 @@ test_blame_commit_keywords()
 	cat <<-EOF >$testroot/view.expected
 	commit $id
 	[1/1] /alpha
-	$(trim_obj_id 32 $(pop_idx 1 $@)) alpha
+	$(trim_obj_id 8 $(pop_idx 1 $@)) alpha
 
 
 
@@ -174,13 +174,13 @@ test_blame_commit_keywords()
 	cat <<-EOF >$testroot/view.expected
 	commit $(pop_idx 8 $@)
 	[1/7] /alpha
-	$(trim_obj_id 32 $(pop_idx 2 $@)) alpha 1
-	$(trim_obj_id 32 $(pop_idx 3 $@)) alpha 2
-	$(trim_obj_id 32 $(pop_idx 4 $@)) alpha 3
-	$(trim_obj_id 32 $(pop_idx 5 $@)) alpha 4
-	$(trim_obj_id 32 $(pop_idx 6 $@)) alpha 5
-	$(trim_obj_id 32 $(pop_idx 7 $@)) alpha 6
-	$(trim_obj_id 32 $(pop_idx 8 $@)) alpha 7
+	$(trim_obj_id 8 $(pop_idx 2 $@)) alpha 1
+	$(trim_obj_id 8 $(pop_idx 3 $@)) alpha 2
+	$(trim_obj_id 8 $(pop_idx 4 $@)) alpha 3
+	$(trim_obj_id 8 $(pop_idx 5 $@)) alpha 4
+	$(trim_obj_id 8 $(pop_idx 6 $@)) alpha 5
+	$(trim_obj_id 8 $(pop_idx 7 $@)) alpha 6
+	$(trim_obj_id 8 $(pop_idx 8 $@)) alpha 7
 
 	EOF
 
@@ -204,10 +204,10 @@ test_blame_commit_keywords()
 	cat <<-EOF >$testroot/view.expected
 	commit $(pop_idx 5 $@)
 	[1/4] /alpha
-	$(trim_obj_id 32 $(pop_idx 2 $@)) alpha 1
-	$(trim_obj_id 32 $(pop_idx 3 $@)) alpha 2
-	$(trim_obj_id 32 $(pop_idx 4 $@)) alpha 3
-	$(trim_obj_id 32 $(pop_idx 5 $@)) alpha 4
+	$(trim_obj_id 8 $(pop_idx 2 $@)) alpha 1
+	$(trim_obj_id 8 $(pop_idx 3 $@)) alpha 2
+	$(trim_obj_id 8 $(pop_idx 4 $@)) alpha 3
+	$(trim_obj_id 8 $(pop_idx 5 $@)) alpha 4
 
 
 
@@ -234,10 +234,10 @@ test_blame_commit_keywords()
 	cat <<-EOF >$testroot/view.expected
 	commit $(pop_idx 5 $@)
 	[1/4] /alpha
-	$(trim_obj_id 32 $(pop_idx 2 $@)) alpha 1
-	$(trim_obj_id 32 $(pop_idx 3 $@)) alpha 2
-	$(trim_obj_id 32 $(pop_idx 4 $@)) alpha 3
-	$(trim_obj_id 32 $(pop_idx 5 $@)) alpha 4
+	$(trim_obj_id 8 $(pop_idx 2 $@)) alpha 1
+	$(trim_obj_id 8 $(pop_idx 3 $@)) alpha 2
+	$(trim_obj_id 8 $(pop_idx 4 $@)) alpha 3
+	$(trim_obj_id 8 $(pop_idx 5 $@)) alpha 4
 
 
 
@@ -271,7 +271,7 @@ test_blame_commit_keywords()
 	cat <<-EOF >$testroot/view.expected
 	commit $(pop_idx 1 $@)
 	[1/1] /alpha
-	$(trim_obj_id 32 $(pop_idx 1 $@)) alpha
+	$(trim_obj_id 8 $(pop_idx 1 $@)) alpha
 
 
 
blob - 4801c9c97f0a63d5a0351ee3ab00ca40e143e5f5
blob + a0945c59f1b465237892c32f9f441c9c57773cca
--- regress/tog/diff.sh
+++ regress/tog/diff.sh
@@ -28,7 +28,7 @@ test_diff_contiguous_commits()
 	local author_time=`git_show_author_time $testroot/repo`
 	local date=`date -u -r $author_time +"%a %b %e %X %Y UTC"`
 	local head_id=`git_show_head $testroot/repo`
-	local head_id_truncated=`trim_obj_id 13 $head_id`
+	local head_id_truncated=`trim_obj_id 27 $head_id`
 	local alpha_id=`get_blob_id $testroot/repo "" alpha`
 
 	cat <<EOF >$TOG_TEST_SCRIPT
@@ -90,7 +90,7 @@ test_diff_arbitrary_commits()
 	(cd $testroot/repo && git add new)
 	git_commit $testroot/repo -m "new file"
 	local head_id=`git_show_head $testroot/repo`
-	local head_id_truncated=`trim_obj_id 13 $head_id`
+	local head_id_truncated=`trim_obj_id 27 $head_id`
 	local alpha_id=`get_blob_id $testroot/repo "" alpha`
 	local new_id=`get_blob_id $testroot/repo "" new`
 
@@ -499,7 +499,7 @@ test_diff_horizontal_scroll()
 	local author_time=`git_show_author_time $testroot/repo`
 	local date=`date -u -r $author_time +"%a %b %e %X %Y UTC"`
 	local head_id=`git_show_head $testroot/repo`
-	local head_id_truncated=`trim_obj_id 13 $head_id`
+	local head_id_truncated=`trim_obj_id 27 $head_id`
 	local alpha_id=`get_blob_id $testroot/repo "" alpha`
 
 	cat <<EOF >$TOG_TEST_SCRIPT
blob - aca1f106300cbd9e2079fa5bedad94acb5af6f36
blob + 58c10dafb6236aba27ddab7d849f0e5fbb825d8b
--- regress/tog/log.sh
+++ regress/tog/log.sh
@@ -135,7 +135,7 @@ test_log_show_author()
 	local author_time=`git_show_author_time $testroot/repo`
 	local date=`date -u -r $author_time +"%a %b %e %X %Y UTC"`
 	local ymd=`date -u -r $author_time +"%F"`
-	local head_id_len8=`trim_obj_id 32 $head_id`
+	local head_id_len8=`trim_obj_id 8 $head_id`
 
 	echo "mod alpha" > $testroot/repo/alpha
 	cd $testroot/repo && git add .
@@ -144,7 +144,7 @@ test_log_show_author()
 	    /dev/null
 
 	local commit1=`git_show_head $testroot/repo`
-	local id1_len8=`trim_obj_id 32 $commit1`
+	local id1_len8=`trim_obj_id 8 $commit1`
 
 	cat <<EOF >$TOG_TEST_SCRIPT
 @		toggle show author
@@ -399,11 +399,11 @@ test_log_commit_keywords()
 
 	cat <<-EOF >$testroot/view.expected
 	commit $(pop_idx 5 $@) [1/5]
-	$ymd $(trim_obj_id 32 $(pop_idx 5 $@)) flan_hacker  commit 4
-	$ymd $(trim_obj_id 32 $(pop_idx 4 $@)) flan_hacker  commit 3
-	$ymd $(trim_obj_id 32 $(pop_idx 3 $@)) flan_hacker  commit 2
-	$ymd $(trim_obj_id 32 $(pop_idx 2 $@)) flan_hacker  commit 1
-	$ymd $(trim_obj_id 32 $(pop_idx 1 $@)) flan_hacker  adding the test tree
+	$ymd $(trim_obj_id 8 $(pop_idx 5 $@)) flan_hacker  commit 4
+	$ymd $(trim_obj_id 8 $(pop_idx 4 $@)) flan_hacker  commit 3
+	$ymd $(trim_obj_id 8 $(pop_idx 3 $@)) flan_hacker  commit 2
+	$ymd $(trim_obj_id 8 $(pop_idx 2 $@)) flan_hacker  commit 1
+	$ymd $(trim_obj_id 8 $(pop_idx 1 $@)) flan_hacker  adding the test tree
 
 
 
@@ -421,13 +421,13 @@ test_log_commit_keywords()
 
 	cat <<-EOF >$testroot/view.expected
 	commit $(pop_idx 7 $@) [1/7]
-	$ymd $(trim_obj_id 32 $(pop_idx 7 $@)) flan_hacker  commit 6
-	$ymd $(trim_obj_id 32 $(pop_idx 6 $@)) flan_hacker  commit 5
-	$ymd $(trim_obj_id 32 $(pop_idx 5 $@)) flan_hacker  commit 4
-	$ymd $(trim_obj_id 32 $(pop_idx 4 $@)) flan_hacker  commit 3
-	$ymd $(trim_obj_id 32 $(pop_idx 3 $@)) flan_hacker  commit 2
-	$ymd $(trim_obj_id 32 $(pop_idx 2 $@)) flan_hacker  commit 1
-	$ymd $(trim_obj_id 32 $(pop_idx 1 $@)) flan_hacker  adding the test tree
+	$ymd $(trim_obj_id 8 $(pop_idx 7 $@)) flan_hacker  commit 6
+	$ymd $(trim_obj_id 8 $(pop_idx 6 $@)) flan_hacker  commit 5
+	$ymd $(trim_obj_id 8 $(pop_idx 5 $@)) flan_hacker  commit 4
+	$ymd $(trim_obj_id 8 $(pop_idx 4 $@)) flan_hacker  commit 3
+	$ymd $(trim_obj_id 8 $(pop_idx 3 $@)) flan_hacker  commit 2
+	$ymd $(trim_obj_id 8 $(pop_idx 2 $@)) flan_hacker  commit 1
+	$ymd $(trim_obj_id 8 $(pop_idx 1 $@)) flan_hacker  adding the test tree
 
 
 	EOF
@@ -443,11 +443,11 @@ test_log_commit_keywords()
 
 	cat <<-EOF >$testroot/view.expected
 	commit $(pop_idx 5 $@) [1/5]
-	$ymd $(trim_obj_id 32 $(pop_idx 5 $@)) flan_hacker  commit 4
-	$ymd $(trim_obj_id 32 $(pop_idx 4 $@)) flan_hacker  commit 3
-	$ymd $(trim_obj_id 32 $(pop_idx 3 $@)) flan_hacker ~commit 2
-	$ymd $(trim_obj_id 32 $(pop_idx 2 $@)) flan_hacker  commit 1
-	$ymd $(trim_obj_id 32 $(pop_idx 1 $@)) flan_hacker  adding the test tree
+	$ymd $(trim_obj_id 8 $(pop_idx 5 $@)) flan_hacker  commit 4
+	$ymd $(trim_obj_id 8 $(pop_idx 4 $@)) flan_hacker  commit 3
+	$ymd $(trim_obj_id 8 $(pop_idx 3 $@)) flan_hacker ~commit 2
+	$ymd $(trim_obj_id 8 $(pop_idx 2 $@)) flan_hacker  commit 1
+	$ymd $(trim_obj_id 8 $(pop_idx 1 $@)) flan_hacker  adding the test tree
 
 
 
@@ -473,7 +473,7 @@ test_log_commit_keywords()
 
 	cat <<-EOF >$testroot/view.expected
 	commit $(pop_idx 1 $@) [1/1]
-	$ymd $(trim_obj_id 32 $(pop_idx 1 $@)) flan_hacker  adding the test tree
+	$ymd $(trim_obj_id 8 $(pop_idx 1 $@)) flan_hacker  adding the test tree
 
 
 
blob - dde6b39fc273ac652a3183be4339de99d649addc
blob + 5cbc7739a8711a9a4c7f9cd93e48ae4fa9be6cf4
--- regress/tog/tree.sh
+++ regress/tog/tree.sh
@@ -54,8 +54,8 @@ test_tree_vsplit_blame()
 	test_init tree_vsplit_blame 120 8
 
 	local head_id=`git_show_head $testroot/repo`
-	local head_id_truncated=`trim_obj_id 8 $head_id`
-	local head_id_short=`trim_obj_id 32 $head_id`
+	local head_id_truncated=`trim_obj_id 32 $head_id`
+	local head_id_short=`trim_obj_id 8 $head_id`
 
 	cat <<EOF >$TOG_TEST_SCRIPT
 KEY_ENTER
@@ -91,8 +91,8 @@ test_tree_hsplit_blame()
 	test_init tree_hsplit_blame 48 24
 
 	local head_id=`git_show_head $testroot/repo`
-	local head_id_truncated=`trim_obj_id 8 $head_id`
-	local head_id_short=`trim_obj_id 32 $head_id`
+	local head_id_truncated=`trim_obj_id 32 $head_id`
+	local head_id_short=`trim_obj_id 8 $head_id`
 
 	cat <<EOF >$TOG_TEST_SCRIPT
 j