For what it is worth I just fixed up the issues in message bus per:
https://github.com/discourse/discourse/commit/41261b32a5099b7e2b87bdc96351cf067d09819a
https://github.com/SamSaffron/message_bus/commit/0664af8b4cfb395b47c3f3b669a874b44d073957
Great catch … moving this to #bug and closing!