title: DistributionNotFound error after upgrading pip
body: <p>In reading about virtualenv <a href="http://www.virtualenv.org/en/latest/index.html">here</a> I realized I didn't have pip 1.3+, so I ran <code>pip install --upgrade pip</code> and now when I run <code>pip --version</code> i get the following:</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 "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/distribute-0.6.34-py2.7.egg/pkg_resources.py", line 2807, in &lt;module&gt;
      parse_requirements(__requires__), Environment()
    File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/distribute-0.6.34-py2.7.egg/pkg_resources.py", line 594, in resolve
      raise DistributionNotFound(req)
  pkg_resources.DistributionNotFound: pip==1.2.1
  </code></pre>
  
  <p>If it helps, or is at all relevant, my <code>$PATH</code> looks like this:</p>
  
  <pre><code>/usr/local/bin:/usr/local/share/python:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/local/git/bin
  </code></pre>
  
  <p>Also, <code>which pip</code> gives me <code>/usr/local/bin/pip</code>.</p>
  
  <p>Not sure what to do about the error. Thanks.</p>