title: No module named packaging
body: <p>I work on Ubuntu 14. I install python3 and pip3.
  When I try to use pip3, I have this error</p>
  
  <pre><code>Traceback (most recent call last):
    File "/usr/local/bin/pip3", line 6, in &lt;module&gt;
      from pkg_resources import load_entry_point
    File "/usr/local/lib/python3.5/dist-packages/pkg_resources/__init__.py", line 70, i
  n &lt;module&gt;
      import packaging.version
  ImportError: No module named 'packaging'
  </code></pre>
  
  <p>Does someone know what is the issue?</p>
  
  <p>Many thanks</p>