title: pip: pulling updates from remote git repository
body: <p>I installed <a href="https://github.com/scikit-learn/scikit-learn" rel="noreferrer">scikit-learn</a> from GitHub a couple of weeks ago:</p>
  
  <pre><code>pip install git+git://github.com/scikit-learn/scikit-learn@master
  </code></pre>
  
  <p>I went to GitHub and there have been several changes to the master branch since then.</p>
  
  <p>How can I update my local installation of <code>scikit-learn</code>?</p>
  
  <p>I tried <code>pip install scikit-learn --upgrade</code> but I got:</p>
  
  <pre><code>Requirement already up-to-date
  Cleaning up ...
  </code></pre>