t3508: add check_head_differs_from() helper function and use it

diff --git a/git-repack.sh b/git-repack.sh
index 1bf239499c7bdb04622ea6fa239bd7c0ace42065..1eb3bca352f38ec3807383cc5fff7f7e62731b2b 100755 (executable)
--- a/git-repack.sh
+++ b/git-repack.sh
@@ -81,7 +81,7 @@ case ",$all_into_one," in
 esac
 
 args="$args $local ${GIT_QUIET:+-q} $no_reuse$extra"
-names=$(git pack-objects --honor-pack-keep --non-empty --all --reflog $args </dev/null "$PACKTMP") ||
+names=$(git pack-objects --keep-true-parents --honor-pack-keep --non-empty --all --reflog $args </dev/null "$PACKTMP") ||
        exit 1
 if [ -z "$names" ]; then
        say Nothing new to pack.