make sure listener is not None

celery/worker/control.py

@@ -21,6 +21,7 @@ class Control(object):
     """
 
     def __init__(self, logger, hostname=None, listener=None):
+        assert listener is not None
         self.logger = logger
         self.hostname = hostname or socket.gethostname()
         self.listener = listener

celery/worker/listener.py

@@ -56,7 +56,8 @@ class CarrotListener(object):
         self.logger = logger
         self.hostname = hostname or socket.gethostname()
         self.control_dispatch = ControlDispatch(logger=logger,
-                                                hostname=self.hostname)
+                                                hostname=self.hostname,
+                                                listener=self)
         self.prefetch_count = SharedCounter(initial_prefetch_count)
         self.event_dispatcher = None
         self.heart = None