Reallow git-rebase --interactive --continue if commit is unnecessary

During git-rebase --interactive's --continue implementation we used
to silently restart the rebase if the user had made the commit
for us.  This is common if the user stops to edit a commit and
does so by amending it.  My recent change to watch git-commit's
exit status broke this behavior.

Thanks to Bernt Hansen for catching it in 1.5.4-rc1.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-rebase--interactive.sh

@@ -372,8 +372,10 @@ do
 			test ! -f "$DOTEST"/amend || git reset --soft HEAD^
 		} &&
 		export GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL GIT_AUTHOR_DATE &&
-		git commit --no-verify -F "$DOTEST"/message -e ||
+		if ! git commit --no-verify -F "$DOTEST"/message -e
+		then
 			die "Could not commit staged changes."
+		fi
 
 		require_clean_work_tree
 		do_rest