qpidd 服务在 Red Hat Satellite 6 上无法启动，并显示消息 "ncat: invalid option -- 'z'"

Issue

• qpidd 服务处于 failed 状态。

  * qpidd.service - An AMQP message broker daemon.
    Loaded: loaded (/usr/lib/systemd/system/qpidd.service; enabled; vendor preset: disabled)
   Drop-In: /etc/systemd/system/qpidd.service.d
            `-wait-for-port.conf
    Active: failed (Result: timeout) since Wed 2020-08-19 11:12:01 EDT; 1h 21min ago
      Docs: man:qpidd(1)
            http://qpid.apache.org/
   Process: 6536 ExecStart=/usr/sbin/qpidd --config /etc/qpid/qpidd.conf (code=exited, status=0/SUCCESS)
  Main PID: 6536 (code=exited, status=0/SUCCESS)
  
  Aug 19 11:11:57 satellite bash[6537]: ncat: invalid option -- 'z'
  Aug 19 11:11:57 satellite bash[6537]: Ncat: Try `--help' or man(1) ncat for more information, usage options and help. QUITTING.
  Aug 19 11:11:58 satellite bash[6537]: ncat: invalid option -- 'z'
  Aug 19 11:11:58 satellite bash[6537]: Ncat: Try `--help' or man(1) ncat for more information, usage options and help. QUITTING.
  Aug 19 11:11:59 satellite bash[6537]: ncat: invalid option -- 'z'
  Aug 19 11:11:59 satellite bash[6537]: Ncat: Try `--help' or man(1) ncat for more information, usage options and help. QUITTING.
  Aug 19 11:12:00 satellite systemd[1]: qpidd.service start-post operation timed out. Stopping.
  Aug 19 11:12:01 satellite systemd[1]: Failed to start An AMQP message broker daemon..
  Aug 19 11:12:01 satellite systemd[1]: Unit qpidd.service entered failed state.
  Aug 19 11:12:01 satellite systemd[1]: qpidd.service failed.
  

• pulp_celerybeat 和 pulp_resource_manager 服务也处于 failed 状态，因为 qpidd 和 candlepin 进入了挂起状态。

• 连接到 satellite 服务器的主机正在收到以下错误消息：

  HTTP error (503 - Service Unavailable): Candlepin is in Suspend mode, please check /status resource to get more details