title: Why isn't setup.py dependency_links doing anything?
body: <p>I have an entry in my <code>setup.py</code> to install a package not hosted on PyPi, that must be compiled using setup.py as it is a C extension. It's not installing when I run <code>python setup.py install</code>, I've checked the logs and I have no idea why.</p>
  
  <pre><code>dependency_links = ['git+https://github.com/liamzebedee/scandir.git#egg=scandir-0.1'],
  </code></pre>