title: NoReverseMatch Django with negative content_type_id
body: <p>I know for some this question may seem similar to other NoReverseMatch Errors, but it isn't</p>
  
  <p>I am using Djangae Framework over Django, to support Google Appengine. I have made a Custom GaeDatastoreUser, extending GaeAbstractBaseUser, and registered the model with <code>admin.site.register()</code>.</p>
  
  <p><strong>models.py</strong></p>
  
  <pre><code>class ChatUser(GaeAbstractBaseUser, PermissionsMixin):
      # ID Constants
  
      class Meta:
          app_label = "chat_auth"
          swappable = 'AUTH_USER_MODEL'
          verbose_name = _('chat user')
          verbose_name_plural = _('chat users')
  
      app_id = models.CharField(_('app_id'), max_length=64, blank=True, null=True)
      gcm_key = models.CharField(_('key'), max_length=128, blank=True, null=True, unique=True)
      mobile = models.CharField(_('mobile'), max_length=10, default="", null=True)
  </code></pre>
  
  <p>Viewing the list of all custom users at <code>/admin/chat_auth/chatuser/</code> on Django's Admin Site is working, but whenever I select a particular user to modify/delete it, I get a</p>
  
  <pre><code>NoReverseMatch at /admin/chat_auth/chatuser/5818821692620800/change/
  Reverse for 'view_on_site' with arguments '()' and keyword arguments '{'object_id': 5818821692620800L, 'content_type_id': -4929820764642951528L}' not found. 1 pattern(s) tried: [u'admin/r/(?P&lt;content_type_id&gt;\\d+)/(?P&lt;object_id&gt;.+)/$']
  </code></pre>
  
  <p>As you can see I am getting a <strong>negative ContentType ID</strong> for any custom admin user (I don't know why). I have changed AUTH_USER_MODEL, and done everything <a href="http://djangae.readthedocs.io/en/latest/gauth/" rel="nofollow">djangae's documentation</a> said.</p>
  
  <p>If I try to use djangae's default GaeDatastoreUser, these links work fine, only when I make a custom user, these links don't work.</p>
  
  <p>Do I need to change something in urls.py, but I don't think so, else they would have provided some documentation on it.</p>
  
  <p>I am sure it's because of negative content_type_id, but what is creating this, is something I am getting</p>
  
  <p><strong>Edit</strong></p>
  
  <p><em>app.yaml</em></p>
  
  <pre><code>- url: /admin.*
    script: {project}.wsgi.application
    secure: always
    login: admin
  </code></pre>