title: Best practice to update Django contrib
body: <p>I'd like to make some changes to <code>def login</code> and <code>def logout</code> in <code>django.contrib.auth</code> <code>__init.py__</code>. Specifically I want to add a mixpanel event to user login and logout.</p>
  
  <p>I know I can do this by editing the file directly, although I assume this is not recommended due to version control / etc. </p>
  
  <p>What's the best / easiest way to override these functions cleanly?</p>