publish to input buffer

currently, the input buffer may not exist when start to publish

weed/mq/broker/broker_grpc_lookup.go

@@ -32,7 +32,6 @@ func (b *MessageQueueBroker) LookupTopicBrokers(ctx context.Context, request *mq
 	ret.Topic = request.Topic
 	if conf, err = b.readTopicConfFromFiler(t); err != nil {
 		glog.V(0).Infof("lookup topic %s conf: %v", request.Topic, err)
-		ret.BrokerPartitionAssignments = conf.BrokerPartitionAssignments
 	} else {
 		err = b.ensureTopicActiveAssignments(t, conf)
 	}

weed/mq/broker/broker_topic_conf_read_write.go

@@ -37,8 +37,11 @@ func (b *MessageQueueBroker) readTopicConfFromFiler(t topic.Topic) (conf *mq_pb.
 	topicDir := fmt.Sprintf("%s/%s/%s", filer.TopicsDir, t.Namespace, t.Name)
 	if err = b.WithFilerClient(false, func(client filer_pb.SeaweedFilerClient) error {
 		data, err := filer.ReadInsideFiler(client, topicDir, "topic.conf")
+		if err == filer_pb.ErrNotFound {
+			return err
+		}
 		if err != nil {
-			return fmt.Errorf("read topic %v partition %v conf: %v", t, err)
+			return fmt.Errorf("read topic.conf of %v: %v", t, err)
 		}
 		// parse into filer conf object
 		conf = &mq_pb.ConfigureTopicResponse{}