bundle: detect if bundle file cannot be created

bundle command silently died with no sign of failure if it
could not create the bundle file. (Eg.: its path resovles to a directory,
or the parent dir is sticky while file already exists and is owned
by someone else.)

Signed-off-by: Csaba Henk <csaba@gluster.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

bundle.c

@@ -372,8 +372,10 @@ int create_bundle(struct bundle_header *header, const char *path,
 	close(rls.in);
 	if (finish_command(&rls))
 		return error ("pack-objects died");
-	if (!bundle_to_stdout)
-		commit_lock_file(&lock);
+	if (!bundle_to_stdout) {
+		if (commit_lock_file(&lock))
+			die_errno("cannot create '%s'", path);
+	}
 	return 0;
 }