title: pip install and custom index url
body: <p>I am getting the following exception while trying to install using <code>pip</code>:</p>
  
  <p><code>Retrying (Retry(total=4, connect=None, read=None, redirect=None)) after connection broken by 'ProtocolError('Connection aborted.', error(111, 'Connection refused'))': /simple/&lt;package&gt;/</code></p>
  
  <p>Where does <code>pip</code> install the packages from?</p>
  
  <p>How do I proxy or use alternate internal site to get these packages?</p>