title: Django-Registration Activation redirect with django.contrib.messages
body: <p>I'm trying to set up my django-registration activation workflow so that when the user hits the activation link it redirects them to the login page with a nice little message using the django messages framework <code>django.contrib.messages</code> </p>
  
  <p>Right now, I've managed to send the user back to the homepage using the <code>success_url</code> parameter:</p>
  
  <pre><code> url(r'activate/(?P&lt;activation_key&gt;\w+)/$',
      activate,
      {'backend': 'registration.backends.default.DefaultBackend', 'success_url':'/'},
          name='registration_activate',
      ),
  </code></pre>
  
  <p>where <code>'/'</code> is the home login view.  I need to set the success message somewhere along the way...perhaps using the <code>extra_context</code> field?</p>