Attempt 1 at fixing

The event isn't being sent to the remote homeserver, so try sending
something to notify of the disinvite.

synapse/handlers/room_member.py

@@ -455,6 +455,7 @@ class RoomMemberHandler(object):
         logger.info("Is host in room? %s" % is_host_in_room)
         logger.info("effective_membership_state %s" % effective_membership_state)
         logger.info("remote_room_hosts %s" % remote_room_hosts)
+        logger.info("hs_is_mine %s" % self.hs.is_mine(target))
 
         if effective_membership_state == Membership.JOIN:
             if requester.is_guest:
@@ -485,6 +486,14 @@ class RoomMemberHandler(object):
                 defer.returnValue(ret)
 
         elif effective_membership_state == Membership.LEAVE:
+            # Send disinvite events to remotes
+            remote_invite = self.hs.is_mine(target)
+            if remote_invite and is_host_in_room:
+                remote_room_hosts = remote_room_hosts + [target.domain]
+                res = yield self._remote_reject_invite(
+                    requester, remote_room_hosts, room_id, target,
+                )
+                defer.returnValue(res)
             if not is_host_in_room:
                 # perhaps we've been invited
                 inviter = yield self._get_inviter(target.to_string(), room_id)