title: pip does not install dependency declared in setup() requires parameter
body: <p>I have a Python project which depends upon the <code>wsgi_intercept</code> package. I added it to the <code>requires</code> parameter from my <code>setup.py</code> file:</p>
  
  <pre><code>from setuptools import setup
  setup( #...
         #...
         requires = [ 'wsgi_intercept',
                 # ...
         ]
   )
  </code></pre>
  
  <p>Then I execute the <code>sdist</code> command:</p>
  
  <pre><code>$ python setup.py sdist upload
  </code></pre>
  
  <p>However, when I install the package with <code>pip</code>, it does not install <code>wsgi_intercept</code> and my package  cannot work correctly.</p>
  
  <p>What am I missing? Should I add another configuration to <code>pip</code>. I read about the <code>pip</code> requirement files but they seem to be used by the deployer, not de distributor.</p>