title: Python-social-auth: disable autoregistering new users
body: <p>I'm experiencing problems with setting PSA not to register a new user on a login.
  The <a href="http://python-social-auth.readthedocs.org/en/latest/pipeline.html#authentication-pipeline" rel="nofollow">documentation</a> says:</p>
  
  <p><code>It’s possible to override it by defining the setting SOCIAL_AUTH_PIPELINE, for example a pipeline that won’t create users, just accept already registered ones would look like this:</code></p>
  
  <pre><code>SOCIAL_AUTH_PIPELINE = (
      'social.pipeline.social_auth.social_user',
      'social.pipeline.social_auth.associate_user',
      'social.pipeline.social_auth.load_extra_data',
      'social.pipeline.user.user_details'
  )
  </code></pre>
  
  <p>I add this code to my settings, try to login via Facebook with an already registered user, and after that I'm redirected to default <code>/accounts/login/#_=_</code> page.</p>
  
  <p>With the default pipeline settings everything works fine and I'm able to log in.</p>