prefix in XREP recv'd message misses MORE flag

src/xrep.cpp

@@ -220,6 +220,7 @@ int zmq::xrep_t::xrecv (zmq_msg_t *msg_, int flags_)
             zmq_assert (rc == 0);
             memcpy (zmq_msg_data (msg_), inpipes [current_in].identity.data (),
                 zmq_msg_size (msg_));
+            msg_->flags = ZMQ_MSG_MORE;
             more_in = true;
             return 0;
         }