A file which could not be updated due to an on-disk obstruction has
the wrong base commit ID recorded after being skipped. This means
future updates won't recognize the file as being out-of-date.

This is similar to the bug fixed in a769b60b, where a file was skipped
due to a conflict.

ok?
 
diff 0899aa6a6c8e8d18bf6449438e40628691db97e9 1541adcbf83735c8d5049f7008cafd52ee01e4f7
blob - 9cc4b321126df2564f860576e790daa70c927295
blob + 515ea2335fcce5c7e77172985fe6dc270ac9cf10
--- lib/worktree.c
+++ lib/worktree.c
@@ -1947,6 +1947,8 @@ update_blob(struct got_worktree *worktree,
 	}
 
 	if (status == GOT_STATUS_OBSTRUCTED) {
+		if (ie)
+			got_fileindex_entry_mark_skipped(ie);
 		err = (*progress_cb)(progress_arg, status, path);
 		goto done;
 	}
blob - 18691664018f8a6afd325e890af93afbcdd51b2b
blob + b75e01faf9766a5bd715ecc25bc1373dc6f135a1
--- regress/cmdline/update.sh
+++ regress/cmdline/update.sh
@@ -2572,7 +2572,114 @@ test_update_file_skipped_due_to_conflict() {
 	test_done "$testroot" "$ret"
 }
 
+test_update_file_skipped_due_to_obstruction() {
+	local testroot=`test_init update_file_skipped_due_to_obstruction`
+	local commit_id0=`git_show_head $testroot/repo`
+	blob_id0=`get_blob_id $testroot/repo "" beta`
 
+	echo "changed beta" > $testroot/repo/beta
+	git_commit $testroot/repo -m "changed beta"
+	local commit_id1=`git_show_head $testroot/repo`
+	blob_id1=`get_blob_id $testroot/repo "" beta`
+
+	got checkout -c $commit_id0 $testroot/repo $testroot/wt > /dev/null
+	ret="$?"
+	if [ "$ret" != "0" ]; then
+		test_done "$testroot" "$ret"
+		return 1
+	fi
+
+	blob_id=`(cd $testroot/wt && got info beta | grep 'blob:' | \
+		cut -d ':' -f 2 | tr -d ' ')`
+	if [ "$blob_id" != "$blob_id0" ]; then
+		echo "file beta has the wrong base blob ID" >&2
+		test_done "$testroot" "1"
+		return 1
+	fi
+
+	commit_id=`(cd $testroot/wt && got info beta | \
+		grep 'based on commit:' | cut -d ':' -f 2 | tr -d ' ')`
+	if [ "$commit_id" != "$commit_id0" ]; then
+		echo "file beta has the wrong base commit ID" >&2
+		test_done "$testroot" "1"
+		return 1
+	fi
+
+	rm $testroot/wt/beta
+	mkdir -p $testroot/wt/beta/psi
+
+	# update to the latest commit; this skips beta
+	(cd $testroot/wt && got update > $testroot/stdout)
+
+	echo "~  beta" > $testroot/stdout.expected
+	echo "Updated to commit $commit_id1" >> $testroot/stdout.expected
+	echo "File paths obstructed by a non-regular file: 1" >> $testroot/stdout.expected
+	cmp -s $testroot/stdout.expected $testroot/stdout
+	ret="$?"
+	if [ "$ret" != "0" ]; then
+		diff -u $testroot/stdout.expected $testroot/stdout
+		test_done "$testroot" "$ret"
+		return 1
+	fi
+
+	blob_id=`(cd $testroot/wt && got info beta | grep 'blob:' | \
+		cut -d ':' -f 2 | tr -d ' ')`
+	if [ "$blob_id" != "$blob_id0" ]; then
+		echo "file beta has the wrong base blob ID" >&2
+		test_done "$testroot" "1"
+		return 1
+	fi
+
+	commit_id=`(cd $testroot/wt && got info beta | \
+		grep 'based on commit:' | cut -d ':' -f 2 | tr -d ' ')`
+	if [ "$commit_id" != "$commit_id0" ]; then
+		echo "file beta has the wrong base commit ID" >&2
+		test_done "$testroot" "1"
+		return 1
+	fi
+
+	# remove the directory which obstructs file beta
+	rm -r $testroot/wt/beta
+
+	# updating to the latest commit should now update beta
+	(cd $testroot/wt && got update > $testroot/stdout)
+	echo "!  beta" > $testroot/stdout.expected
+	echo "Updated to commit $commit_id1" >> $testroot/stdout.expected
+	cmp -s $testroot/stdout.expected $testroot/stdout
+	ret="$?"
+	if [ "$ret" != "0" ]; then
+		diff -u $testroot/stdout.expected $testroot/stdout
+		test_done "$testroot" "$ret"
+		return 1
+	fi
+
+	blob_id=`(cd $testroot/wt && got info beta | grep 'blob:' | \
+		cut -d ':' -f 2 | tr -d ' ')`
+	if [ "$blob_id" != "$blob_id1" ]; then
+		echo "file beta has the wrong base blob ID" >&2
+		test_done "$testroot" "1"
+		return 1
+	fi
+
+	commit_id=`(cd $testroot/wt && got info beta | \
+		grep 'based on commit:' | cut -d ':' -f 2 | tr -d ' ')`
+	if [ "$commit_id" != "$commit_id1" ]; then
+		echo "file beta has the wrong base commit ID: $commit_id" >&2
+		test_done "$testroot" "1"
+		return 1
+	fi
+
+	echo "changed beta" > $testroot/content.expected
+	cat $testroot/wt/beta > $testroot/content
+	cmp -s $testroot/content.expected $testroot/content
+	ret="$?"
+	if [ "$ret" != "0" ]; then
+		diff -u $testroot/content.expected $testroot/content
+	fi
+	test_done "$testroot" "$ret"
+}
+
+
 test_parseargs "$@"
 run_test test_update_basic
 run_test test_update_adds_file
@@ -2614,3 +2721,4 @@ run_test test_update_deletes_symlink
 run_test test_update_symlink_conflicts
 run_test test_update_single_file
 run_test test_update_file_skipped_due_to_conflict
+run_test test_update_file_skipped_due_to_obstruction