title: Starting supervisor generates error
body: <p>For this command: <strong>service supervisor restart</strong> I'm getting this:</p>
  
  <pre><code>Restarting supervisor: Traceback (most recent call last):
    File "/usr/bin/supervisord", line 5, in &lt;module&gt;
      from pkg_resources import load_entry_point
    File "build/bdist.linux-x86_64/egg/pkg_resources/__init__.py", line 3019, in &lt;module&gt;
    File "build/bdist.linux-x86_64/egg/pkg_resources/__init__.py", line 3003, in _call_aside
    File "build/bdist.linux-x86_64/egg/pkg_resources/__init__.py", line 3032, in _initialize_master_working_set
    File "build/bdist.linux-x86_64/egg/pkg_resources/__init__.py", line 657, in _build_master
    File "build/bdist.linux-x86_64/egg/pkg_resources/__init__.py", line 670, in _build_from_requirements
    File "build/bdist.linux-x86_64/egg/pkg_resources/__init__.py", line 849, in resolve
  pkg_resources.DistributionNotFound: The 'supervisor==3.0' distribution was not found and is required by the application
  </code></pre>
  
  <p>and have no idea what to do.
  I've upgraded the system using apt-get update and apt-get upgrade and after I started receiving this.</p>