title: 'AnonymousUser' object has no attribute 'backend'
body: <p>Using django-socialregistration, got following error:</p>
  
  <pre><code>'AnonymousUser' object has no attribute 'backend'
  </code></pre>
  
  <p>How,</p>
  
  <ol>
  <li>I click on facebook connect url.</li>
  <li>That took me Facebook and ask me to login. So I did, asked permission, I granted.</li>
  <li>After that it redirect me to my site. And ask to setup. I provide user and email address.</li>
  <li>Once I submit, got error like above:</li>
  </ol>
  
  <p>Trace point:</p>
  
  <pre><code>path/to_file/socialregistration/views.py in post
  128.      self.login(request, user)
  </code></pre>
  
  <p>Do anybody know, what's wrong?</p>