title: package is installed via pip in wrong (src) directory instead of site packages
body: <p>I'm installing <a href="https://github.com/mr-stateradio/django-exchange" rel="noreferrer">this</a> package into a virtualenv using virtualenvwrapper and pip with this command:</p>
  
  <pre><code>pip install -e git+git://github.com/mr-stateradio/django-exchange.git#egg=django_exchange-master
  </code></pre>
  
  <p>Interestingly the package is then placed into a src folder, and not into the site-packages folder which I would have expected. The package is placed into this folder:</p>
  
  <pre><code>&lt;path-to-my-virtual-env&gt;/testenv/src/django-exchange-master/exchange
  </code></pre>
  
  <p>Instead of this:</p>
  
  <pre><code>&lt;path-to-my-virtual-env&gt;/testenv/lib/python2.7/site-packages
  </code></pre>
  
  <p>I assume something is wrong with the pip install command I'm using or with the setup.py of the package. </p>