You can do this more succinctly with
```
yield task.deferLater(reactor, 0, lambda : None)
```
I'd very much like to find some way to do something more reliable than "wait a bit".  This will most likely fail mysteriously on a small fraction of test runs.  Is this waiting for the PB port to open?  If so, that could be polled from `self.master.pbmanager`.