Avoid spurious error messages on error mistakes.

MadCoder · gitster · commit 12dd1112886f · 2009-01-13T00:21:31.000-08:00
Prior to that, if the user chose "squash" as a first action, the stderr
looked like:

    grep: /home/madcoder/dev/scm/git/.git/rebase-merge/done: No such file or directory
    Cannot 'squash' without a previous commit

Now the first line is gone.

Signed-off-by: Pierre Habouzit &lt;madcoder@debian.org&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
@@ -309,7 +309,7 @@ do_next () {
 	squash|s)
 		comment_for_reflog squash
 
-		has_action "$DONE" ||
+		test -f "$DONE" && has_action "$DONE" ||
 			die "Cannot 'squash' without a previous commit"
 
 		mark_action_done
