title: Running `pip` in the Google Cloud Shell causes ImportError
body: <p>When I create a new project in Google Cloud Console and just try to run</p>
  
  <pre><code>pip
  </code></pre>
  
  <p>I get this error:</p>
  
  <pre><code>    Traceback (most recent call last):
    File "/usr/local/bin/pip", line 5, in &lt;module&gt;
      from pkg_resources import load_entry_point
    File "/home/sguergachi/.local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 70, in &lt;module&gt;
      import packaging.version
  ImportError: No module named packaging.version
  </code></pre>
  
  <p>I'm not sure how to fix this. Reinstalling doesn't seem to be an option for google cloud as it would for local environment.</p>