Bug 8741 contains the UDT dissector, which is a UDP protocol that may carry its own payload. The (new-style) dissector was explicitly calling the data dissector and returning the full tvb length. I thought one of the benefits of the new-style dissectors was that the "parent" dissector could see that the tvb wasn't fully dissected. And if it wasn't fully dissected, the parent could try to dissect the rest (which would probably just end up in calling the data dissector). This would lessen the burder on the parent's payload dissector to make sure the full tvb was dissected (if it didn't need to be).
So is there a bug in the UDP dissector (in decode_udp_ports), that it's not calling the data dissector is there is data remaining on the tvb? Or should all UDP protocols have to explicitly get a handle to the data dissector to call it? Was this functionality waiting on all dissectors to be converted to the "new style"?