t3508: add check_head_differs_from() helper function and use it

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index 5b6278572a48569a806a5a976cdd08eb7c117fb7..51dd0d67ba951873df4f26b1707a1e8a713082b9 100644 (file)
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -1,3 +1,4 @@
+#!/bin/sh
 # git-mergetool--lib is a library for common merge tool functions
 diff_mode() {
        test "$TOOL_MODE" = diff