Fix bug where we didn't inform the NotificataionListeners about new rooms they...

Fix bug where we didn't inform the NotificataionListeners about new rooms they have been subscribed to. This meant that the listeners didn't clean themselves up fully from all the dicts

synapse/notifier.py

@@ -427,3 +427,6 @@ class Notifier(object):
 
         listeners = self.room_to_listeners.setdefault(room_id, set())
         listeners |= new_listeners
+
+        for l in new_listeners:
+            l.rooms.add(room_id)