Bad file descriptor during cleanup_fds

I sometimes get (when quitting supervisor with CTRL+C) the following trace:

^C2018-06-13 22:32:21,219 WARN received SIGINT indicating exit request
2018-06-13 22:32:21,220 INFO waiting for web to die
2018-06-13 22:32:21,270 INFO stopped: web (exit status 0)
2018-06-13 22:32:21,270 INFO Closing socket tcp://0.0.0.0:8000
Exception ignored in: <bound method tail_f_producer.__del__ of <supervisor.http.tail_f_producer object at 0x7f599b85e2e8>>
Traceback (most recent call last):
  File "/home/florian/.local/lib/python3.6/site-packages/supervisor/http.py", line 649, in __del__
    self._close()
  File "/home/florian/.local/lib/python3.6/site-packages/supervisor/http.py", line 675, in _close
    self.file.close()
OSError: [Errno 9] Bad file descriptor

my supervisor config file:

[supervisord]
logfile = /tmp/supervisord.log

[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

[fcgi-program:web]
# Patched gunicorn supporting fcgi-program: https://github.com/benoitc/gunicorn/pull/1809
command = python -m gunicorn.app.wsgiapp --reuse-port --workers 4 --bind fd://0 test:application
directory = %(here)s
socket = tcp://0.0.0.0:8000

I cannot yet reliably reproduce :/