title: When run django server then facing traceback like TypeError: Error when calling the metaclass bases
body: <p><strong>I have upgrade django 1.5 to 1.6 version, due to this reason i am facing this kind of traceback</strong></p>
  
  <pre><code>Traceback (most recent call last):
        File "/usr/lib/python2.7/wsgiref/handlers.py", line 85, in run
          self.result = application(self.environ, self.start_response)
        File "/usr/local/lib/python2.7/dist-packages/django/contrib/staticfiles/handlers.py", line 67, in __call__
          return self.application(environ, start_response)
        File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/wsgi.py", line 187, in __call__
          self.load_middleware()
        File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py", line 49, in load_middleware
          mw_instance = mw_class()
        File "/usr/local/lib/python2.7/dist-packages/django/middleware/locale.py", line 24, in __init__
          for url_pattern in get_resolver(None).url_patterns:
        File "/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py", line 346, in url_patterns
          patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
        File "/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py", line 341, in urlconf_module
          self._urlconf_module = import_module(self.urlconf_name)
        File "/usr/local/lib/python2.7/dist-packages/django/utils/importlib.py", line 40, in import_module
          __import__(name)
        File "/home/hsa/Documents/Django/juicypebble/juicypebble/urls.py", line 6, in &lt;module&gt;
          admin.autodiscover()
        File "/usr/local/lib/python2.7/dist-packages/django/contrib/admin/__init__.py", line 29, in autodiscover
          import_module('%s.admin' % app)
        File "/usr/local/lib/python2.7/dist-packages/django/utils/importlib.py", line 40, in import_module
          __import__(name)
        File "/usr/local/lib/python2.7/dist-packages/cms/admin/__init__.py", line 2, in &lt;module&gt;
          import pageadmin
        File "/usr/local/lib/python2.7/dist-packages/cms/admin/pageadmin.py", line 30, in &lt;module&gt;
          from cms.admin.change_list import CMSChangeList
        File "/usr/local/lib/python2.7/dist-packages/cms/admin/change_list.py", line 7, in &lt;module&gt;
          from cms.utils.permissions import get_user_sites_queryset
        File "/usr/local/lib/python2.7/dist-packages/cms/utils/permissions.py", line 4, in &lt;module&gt;
          from cms.plugin_pool import plugin_pool
        File "/usr/local/lib/python2.7/dist-packages/cms/plugin_pool.py", line 3, in &lt;module&gt;
          from cms.plugin_base import CMSPluginBase
        File "/usr/local/lib/python2.7/dist-packages/cms/plugin_base.py", line 85, in &lt;module&gt;
          class CMSPluginBase(admin.ModelAdmin):
        File "/usr/local/lib/python2.7/dist-packages/cms/plugin_base.py", line 30, in __new__
          return super_new(cls, name, bases, attrs)
        File "/usr/local/lib/python2.7/dist-packages/django/forms/widgets.py", line 137, in __new__
          attrs)
      TypeError: Error when calling the metaclass bases
          metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases
      [07/Apr/2014 07:01:32] "GET / HTTP/1.1" 500 59
  </code></pre>