use the channels of the event when wait()-ing

circuits/core/manager.py

@@ -490,6 +490,7 @@ def waitEvent(self, event, *channels, **kwargs):  # noqa
         if isinstance(event, Event):
             event_object = event
             event_name = event.name
+            channels = event.channels or channels
         else:
             event_object = None
             event_name = event