and here's the regress bits too

diff /home/op/w/gotd
commit - bcfa81c7d30bcafdd71a03b1ca679ad735fd0a80
path + /home/op/w/gotd
blob - 4febc6122401f6f47ac76d69b9db67f578229f64
file + regress/cmdline/common.sh
--- regress/cmdline/common.sh
+++ regress/cmdline/common.sh
@@ -50,7 +50,12 @@ maybe_pack_repo()
 {
 	local repo="$1"
 	if [ -n "$GOT_TEST_PACK" ]; then
-		(cd $repo && gotadmin pack -a > /dev/null)
+		arg=""
+		if [ "$GOT_TEST_PACK" = "ref-delta" ]; then
+			arg="-D"
+		fi
+
+		(cd $repo && gotadmin pack -a $arg > /dev/null)
 		(cd $repo && gotadmin cleanup -a -q)
 	fi
 }
blob - 40a3eba474b4a8fe35b9669596fb6994cc3739ae
file + util/got-build-regress.sh
--- util/got-build-regress.sh
+++ util/got-build-regress.sh
@@ -130,6 +130,19 @@ printf "\n\n\tTesting a release build\n\n" >> build.lo
 	exit 0
 fi
 
+printf "\n\n\tRunning tests with pack files using ref-delta\n\n" >> build.log
+log_cmd regress.log env PATH=$HOME/bin:$PATH make regress GOT_TEST_ROOT="$testroot" GOT_TEST_PACK=ref-delta
+regress_status="$?"
+cat regress.log >> build.log
+egrep "test.*failed" regress.log > failures.log
+regress_failure_grep="$?"
+if [ "$regress_status" -ne 0 -o "$regress_failure_grep" -eq 0 ]; then
+	printf "\n\n\t Test failures:\n\n" >> build.log
+	cat failures.log >> build.log
+	mail $fromaddr_arg -s "$prog regress failure" $recipients < build.log
+	exit 0
+fi
+
 printf "\n\n\tTesting a release build\n\n" >> build.log
 log_cmd build.log make clean
 log_cmd build.log make obj