title: Logged in users still see login page (django auth)
body: <p>I'm using <code>django.contrib.auth</code> to handle user authentication in my django project. In order to log in, I have</p>
  
  <pre><code>from django.contrib.auth.views import login, logout
  
  # ...
  
  url(r'^login/', login, name='login'),
  url(r'^logout/', logout, {'next_page': '/'}, name='logout'),
  </code></pre>
  
  <p>in my main project's <code>urls.py</code>.</p>
  
  <p>So far, so good. However, I notice that <em>after</em> logging in, if I access <code>/login/</code>, I still see the login page, and am able to log in as another user. This seems like counter-intuitive behavior -- most websites will either show an error or redirect you to the homepage if you attempt to access the login page while logged in.</p>
  
  <p><strong>I'm using the builtin models / views, and so as far as I know I have no easy way of altering the views.</strong> Is there a simple way of gaining this functionality (i.e. preventing access to the login form if logged in), or is the best way simply to modify the template to only show the form if not logged in?</p>