title: OSError: [Errno 13] Permission denied when updating setuptools
body: <p>I'm trying to update setuptools using homebrew but I keep getting an error that says:</p>
  
  <pre><code>OSError: [Errno 13] Permission denied: '/Library/Python/2.7/site-packages/setuptools-1.1.3-py2.7.egg'
  </code></pre>
  
  <p>How do I allow my computer to make changes to that file so I can update setuptools?</p>