message: Fix the redis error msg.
diff: @@ -3958,6 +3958,11 @@ static void swoole_redis_coro_parse_result(swRedisClient *redis, zval* return_va
  case REDIS_REPLY_ERROR:
  ZVAL_FALSE(return_value);
  + if (redis->context->err == 0)
  + {
  + redis->context->err = -1;
  + redis->context->errstr = reply->str;
  + }
  zend_update_property_long(swoole_redis_coro_class_entry_ptr, redis->object, ZEND_STRL("errCode"), redis->context->err TSRMLS_CC);
  zend_update_property_string(swoole_redis_coro_class_entry_ptr, redis->object, ZEND_STRL("errMsg"), redis->context->errstr TSRMLS_CC);
  break;
  