[PATCH v4 14/27] sequencer.c: use ref transactions for all ref updates

@@ -272,19 +272,30 @@ static int error_dirty_index(struct replay_opts *opts)
 static int fast_forward_to(const unsigned char *to, const unsigned char *from,
 			int unborn, struct replay_opts *opts)
 {
-	struct ref_lock *ref_lock;
+	struct ref_transaction *transaction;
 	struct strbuf sb = STRBUF_INIT;
-	int ret;
+	struct strbuf err = STRBUF_INIT;
 
 	read_cache();
 	if (checkout_fast_forward(from, to, 1))
 		exit(1); /* the callee should have complained already */
-	ref_lock = lock_any_ref_for_update("HEAD", unborn ? null_sha1 : from,
-					   0, NULL);
+
 	strbuf_addf(&sb, "%s: fast-forward", action_name(opts));
-	ret = write_ref_sha1(ref_lock, to, sb.buf);
+
+	transaction = ref_transaction_begin();
+	if ((!transaction ||
+	    ref_transaction_update(transaction, "HEAD", to, from,
+				   0, !unborn)) ||
+	    (ref_transaction_commit(transaction, sb.buf, &err) &&
+	     !(transaction = NULL))) {
+		ref_transaction_rollback(transaction);
+		strbuf_release(&sb);
+		return error(_("HEAD: Could not fast-forward: %s\n"),
+			     strbuf_detach(&err, NULL));
+	}
+
 	strbuf_release(&sb);
-	return ret;
+	return 0;
 }
 
 static int do_recursive_merge(struct commit *base, struct commit *next,