title: Django Admin's "view on site" points to example.com instead of my domain
body: <p>I added a <code>get_absolute_url</code> function to one of my models.</p>
  
  <pre><code>def get_absolute_url(self):
      return '/foo/bar' 
  </code></pre>
  
  <p>The admin site picks it up and adds a "view on site" link to the detail page for that object (when I put a real URL there instead of "/foo/bar").</p>
  
  <p>The problem is instead of going to <code>http://localhost:8000/foo/bar</code>, it goes to <code>http://example.com/foo/bar</code>.</p>
  
  <p>What am I doing wrong?</p>