Log ref changes made by quiltimport.

When importing a quilt patch to a branch which has a reflog record
the update to HEAD with a log message indicating the change was
made by quiltimport and what patch caused the change.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git-quiltimport.sh

@@ -112,7 +112,7 @@ for patch_name in $(cat "$QUILT_PATCHES/series" | grep -v '^#'); do
 		git-apply --index -C1 "$tmp_patch" &&
 		tree=$(git-write-tree) &&
 		commit=$((echo "$SUBJECT"; echo; cat "$tmp_msg") | git-commit-tree $tree -p $commit) &&
-		git-update-ref HEAD $commit || exit 4
+		git-update-ref -m "quiltimport: $patch_name" HEAD $commit || exit 4
 	fi
 done
 rm -rf $tmp_dir || exit 5