compat: Add simplified merge sort implementation from glibc

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index fbb948d6fd42091acade3fa807d5ff250cea651b..ff716cabb084526ddb5655c3b7c6dd02f4ed1b39 100755 (executable)
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -114,7 +114,6 @@ orig_namespace=refs/original/
 force=
 while :
 do
-       test $# = 0 && usage
        case "$1" in
        --)
                shift
@@ -213,7 +212,7 @@ GIT_WORK_TREE=.
 export GIT_DIR GIT_WORK_TREE
 
 # The refs should be updated if their heads were rewritten
-git rev-parse --no-flags --revs-only --symbolic-full-name "$@" |
+git rev-parse --no-flags --revs-only --symbolic-full-name --default HEAD "$@" |
 sed -e '/^^/d' >"$tempdir"/heads
 
 test -s "$tempdir"/heads ||