def update_pool(self, old_pool, pool, service):
        """Update lb pool."""
        LOG.debug("Updating pool")
        if service.get("listeners"):
            target_listener = service["listeners"][0]
            target_listener["provisioning_status"] = "PENDING_UPDATE"
        self._common_service_handler(service)
        return self._update_target(service,
                                   self._update_pool_status,
                                   service["pools"])