Sometimes even cluster_member has responded new_node.meet,
        cluster_memeber.nodes() are still not updated

def _wait_nodes_updated(self, cluster_member, new_nodes):
        '''Sometimes even cluster_member has responded new_node.meet,
        cluster_memeber.nodes() are still not updated
        '''
        while True:
            known_nodes = [n['name'] for n in cluster_member.nodes()]
            added_nodes = [n.name for n in new_nodes]
            if len(set(known_nodes) & set(added_nodes)) == len(added_nodes):
                break;
            logger.info('waiting for adding new nodes in `cluster nodes`')
            time.sleep(1)