title: s6 overlay s6-svc supervisor not listening
body: <pre><code>root@0cd6bfb7e363 app]# s6-svc /etc/services.d/uwsgi/
  s6-svc: fatal: unable to control /etc/services.d/uwsgi/: supervisor not listening
  
  [root@0cd6bfb7e363 app]# s6-svc -r /etc/services.d/uwsgi/
  s6-svc: fatal: unable to control /etc/services.d/uwsgi/: supervisor not listening
  
  </code></pre>
  <p><strong>however</strong></p>
  <pre><code>[root@0cd6bfb7e363 app]# ps aufx
  USER         PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
  root           1  0.0  0.0    204     4 pts/0    Ss   01:42   0:00 s6-svscan -t0 /var/run/s6/services
  root          30  0.0  0.0    188     8 pts/0    S    01:42   0:00 foreground  if   /etc/s6/init/init-stage2-redirfd   foreground    if     if      s6-echo      -n      --
  root          40  0.0  0.0    184     4 pts/0    S    01:42   0:00  \_ foreground  s6-setsid  -gq  --  with-contenv  backtick  -D  0  -n  S6_LOGGING   printcontenv   S6_LO
  root         261  0.0  0.0  15540  3864 pts/0    S    01:42   0:00      \_ /bin/bash
  root         516  0.0  0.0  55204  3932 pts/0    R+   01:52   0:00          \_ ps aufx
  root          31  0.0  0.0    204     4 pts/0    S    01:42   0:00 s6-supervise s6-fdholderd
  root         241  0.0  0.0    204     4 pts/0    S    01:42   0:00 s6-supervise nginx
  root         246  0.0  0.0  56840  7228 ?        Ss   01:42   0:00  \_ nginx: master process /usr/sbin/nginx
  nginx        267  0.0  0.0  57484  5048 ?        S    01:42   0:00      \_ nginx: worker process
  root         243  0.0  0.0    204     4 pts/0    S    01:42   0:00 s6-supervise uwsgi
  root         245  0.0  0.0  15140  3012 ?        Ss   01:42   0:00  \_ bash ./run
  root         255  0.2  0.0 259944 82060 ?        S    01:42   0:01      \_ uwsgi /etc/uwsgi.ini
  root         339  0.0  0.0 259944 70452 ?        S    01:43   0:00          \_ uwsgi /etc/uwsgi.ini
  root         340  0.0  0.0 259944 70452 ?        S    01:43   0:00          \_ uwsgi /etc/uwsgi.ini
  root         341  0.1  0.0 297500 96408 ?        S    01:43   0:01          \_ uwsgi /etc/uwsgi.ini
  root         342  0.0  0.0 259944 70452 ?        S    01:43   0:00          \_ uwsgi /etc/uwsgi.ini
  </code></pre>
  <p>What could be wrong?</p>