Called after agent has switched a shard. Alert poster needs an update
        in this case, bacause otherwise its posting to lobby instead of the
        shard exchange.

def _fix_alert_poster(self, state, shard):
        '''
        Called after agent has switched a shard. Alert poster needs an update
        in this case, bacause otherwise its posting to lobby instead of the
        shard exchange.
        '''
        recp = recipient.Broadcast(AlertPoster.protocol_id, shard)
        state.alerter.update_recipients(recp)