supervisor run error After supervisorctl reload command execute twice

[zhuqiuyang]

why supervisorctl reload cmd will lead supervisor report err and shut down.
i prepare use it to daemon my golang application.

[mnaberez]

Reproduce Instructions

Start supervisord in the foreground with this config:

$ cat supervisord.conf
[supervisord]

[inet_http_server]
port = 127.0.0.1:9001

[supervisorctl]
serverurl = http://127.0.0.1:9001

[rpcinterface:supervisor]
supervisor.rpcinterface_factory = supervisor.rpcinterface:make_main_rpcinterface

$ supervisord -n -c supervisord.conf 
2016-12-29 14:09:05,033 INFO Increased RLIMIT_NOFILE limit to 1024
2016-12-29 14:09:05,044 INFO RPC interface 'supervisor' initialized
2016-12-29 14:09:05,045 CRIT Server 'inet_http_server' running without any HTTP authentication checking
2016-12-29 14:09:05,045 INFO supervisord started with pid 22137

While supervisord is still running, in another terminal:

$ supervisorctl -c supervisord.conf reload
Restarted supervisord

$ supervisorctl -c supervisord.conf reload
Restarted supervisord

After the second reload, supervisord will crash:

2016-12-29 14:11:49,406 INFO RPC interface 'supervisor' initialized
2016-12-29 14:11:49,406 CRIT Server 'inet_http_server' running without any HTTP authentication checking
2016-12-29 14:11:49,406 INFO supervisord started with pid 22235
2016-12-29 14:11:50,741 INFO RPC interface 'supervisor' initialized
2016-12-29 14:11:50,741 CRIT Server 'inet_http_server' running without any HTTP authentication checking
2016-12-29 14:11:50,741 INFO supervisord started with pid 22235
Traceback (most recent call last):
  File "/usr/local/bin/supervisord", line 11, in <module>
    load_entry_point('supervisor', 'console_scripts', 'supervisord')()
  File "/path/to/supervisor/supervisord.py", line 361, in main
    go(options)
  File "/path/to/supervisor/supervisord.py", line 371, in go
    d.main()
  File "/path/to/supervisor/supervisord.py", line 82, in main
    self.run()
  File "/path/to/supervisor/supervisord.py", line 99, in run
    self.runforever()
  File "/path/to/supervisor/supervisord.py", line 214, in runforever
    r, w = self.options.poller.poll(timeout)
  File "/path/to/supervisor/poller.py", line 176, in poll
    kevents = self._kqueue.control(None, self.max_events, timeout)
OSError: [Errno 9] Bad file descriptor