PGM late joiners would start receiving a complete message rather than a message part

src/zmq_encoder.cpp

@@ -98,13 +98,15 @@ bool zmq::zmq_encoder_t::message_ready ()
     if (size < 255) {
         tmpbuf [0] = (unsigned char) size;
         tmpbuf [1] = (in_progress.flags & ~ZMQ_MSG_SHARED);
-        next_step (tmpbuf, 2, &zmq_encoder_t::size_ready, true);
+        next_step (tmpbuf, 2, &zmq_encoder_t::size_ready,
+            !(in_progress.flags & ZMQ_MSG_TBC));
     }
     else {
         tmpbuf [0] = 0xff;
         put_uint64 (tmpbuf + 1, size);
         tmpbuf [9] = (in_progress.flags & ~ZMQ_MSG_SHARED);
-        next_step (tmpbuf, 10, &zmq_encoder_t::size_ready, true);
+        next_step (tmpbuf, 10, &zmq_encoder_t::size_ready,
+            !(in_progress.flags & ZMQ_MSG_TBC));
     }
     return true;
 }