title: celery supervisor returns "no such file or directory" error
body: <p>I'm using supervisor to daemonize my django project. If I don't start celery from supervisor but start from shell <code>(celery -A proj worker --app=proj.celery:app --loglevel=INFO)</code> everything works fine. When I daemonize the celery program, task logs <code>No such file or directory</code> and finishes immediately. </p>
  
  <p>There isn't any other problem, workers are alive, <code>supervisorctl</code> status celery is <code>RUNNING</code> etc. Whats the problem?</p>
  
  <p>My <code>celery_err.log</code> file content:</p>
  
  <pre><code>[2018-04-08 15:24:01,121: INFO/MainProcess] Connected to redis://localhost:6379//
  [2018-04-08 15:24:01,131: INFO/MainProcess] mingle: searching for neighbors
  [2018-04-08 15:24:02,135: INFO/MainProcess] mingle: all alone
  [2018-04-08 15:24:02,143: WARNING/MainProcess] /home/ali/Desktop/proj/projenv/local/lib/python2.7/site-packages/celery/fixups/django.py:265: UserWarning: Using settings.DEBUG leads to a memory leak, never use this setting in production environments!
    warnings.warn('Using settings.DEBUG leads to a memory leak, never '
  [2018-04-08 15:24:02,143: WARNING/MainProcess] celery@debian ready.
  [2018-04-08 15:24:32,789: INFO/MainProcess] Received task: task_proj[441f7326-c847-4a29-a65d-543b8794e7a3]
  [2018-04-08 15:24:32,797: INFO/Worker-2] task_proj[441f7326-c847-4a29-a65d-543b8794e7a3]: Sent scan request successfully
  [2018-04-08 15:24:32,831: WARNING/Worker-2] [Errno 2] No such file or directory
  [2018-04-08 15:24:32,843: WARNING/Worker-2] [Errno 2] No such file or directory
  </code></pre>
  
  <p>​
  my <code>supervisord.conf</code> file content:</p>
  
  <pre><code>[program:proj]
  environment=LANG=en_US.UTF-8,LC_ALL=en_US.UTF-8 ,PATH="/var/www/proj/projenv/bin", PROJ_ENV_FILE="/var/www/proj/proj.env",VIRTUAL_ENV="/var/www/proj/projenv",PYTHONPATH="/var/www/proj/projenv/lib/python:/var/www/proj/projenv/lib/python/site-packages"
  command = /var/www/proj/bin/gunicorn_start                           
  user = root                                                                 
  redirect_stderr = true                                                     
  stdout_logfile=/var/www/proj/logs/django.log
  stderr_logfile=/var/www/proj/logs/django_err.log
  ​
  [program:redis]
  command = /etc/redis-4.0.2/src/redis-server
  ​
  ​
  [program:celery]
  environment=LANG=en_US.UTF-8,LC_ALL=en_US.UTF-8 ,PATH="/var/www/proj/projenv/bin", PROJ_ENV_FILE="/var/www/proj/proj.env",VIRTUAL_ENV="/var/www/proj/projenv",PYTHONPATH="/var/www/proj/projenv/lib/python:/var/www/proj/projenv/lib/python/site-packages"
  directory=/var/www/proj/proj
  command = /var/www/proj/projenv/bin/celery -A proj worker --app=proj.celery:app --loglevel=INFO
  user = root
  redirect_stderr = true                                                       
  stdout_logfile = /var/www/proj/logs/celery.log
  stderr_logfile = /var/www/proj/logs/celery_err.log
  autostart=true
  autorestart=true
  startsecs=10
  stopwaitsecs=600
  </code></pre>