set() return True when got ConnectionError

[liuguoshun]

when set() got ConnectionError ,return value should be nil. but still return True.

1. this is how to get connection.

cluster_nodes = [
    {"host": "10.x.x.x", "port": "6390"},
    {"host": "10.x.x.x", "port": "6391"},
    {"host": "10.x.x.x", "port": "6390"},
    {"host": "10.x.x.x", "port": "6391"},
    {"host": "10.x.x.x", "port": "6390"},
    {"host": "10.x.x.x", "port": "6391"},
]
rc = RedisCluster(startup_nodes=cluster_nodes, decode_responses=True, socket_connect_timeout=3)

2.this is part of my code.

def start_failover_node(node, type):
    if rc.set("%s_fail" % node, lanip, ex=180, nx=True):
        logger.error(
            "got X failover lock,start failover %s with %s error." % (node, type))
        os_cmd = "nohup python3 wmha_failover.py %s %s >/dev/null 2>&1 &" % (
            node, type)
        os.system(os_cmd)
    else:
        monitor_host = rc.get("%s_fail" % node)
        logger.warning(
            "monitor host %s failover node %s with %s error." % (monitor_host, node, type))

3.this is log

2021-06-07 12:05:15,822 - [ERROR] ConnectionError
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/redis_py_cluster-2.1.0-py3.6.egg/rediscluster/client.py", line 626, in _execute_command
    return self.parse_response(connection, command, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/redis-3.5.3-py3.6.egg/redis/client.py", line 915, in parse_response
    response = connection.read_response()
  File "/usr/local/lib/python3.6/site-packages/redis-3.5.3-py3.6.egg/redis/connection.py", line 739, in read_response
    response = self._parser.read_response()
  File "/usr/local/lib/python3.6/site-packages/redis-3.5.3-py3.6.egg/redis/connection.py", line 324, in read_response
    raw = self._buffer.readline()
  File "/usr/local/lib/python3.6/site-packages/redis-3.5.3-py3.6.egg/redis/connection.py", line 256, in readline
    self._read_from_socket()
  File "/usr/local/lib/python3.6/site-packages/redis-3.5.3-py3.6.egg/redis/connection.py", line 201, in _read_from_socket
    raise ConnectionError(SERVER_CLOSED_CONNECTION_ERROR)
redis.exceptions.ConnectionError: Connection closed by server.
2021-06-07 12:05:16,073 - [ERROR] got X failover lock,start failover 10.200.30.100_3306 with instance error.