Comment 2 for bug 1660344

Full log trace:

 [Mon Jan 30 13:50:09.497389 2017] [wsgi:error] [pid 11554:tid 140090457696000] Internal Server Error: /auth/login/
 [Mon Jan 30 13:50:09.497440 2017] [wsgi:error] [pid 11554:tid 140090457696000] Traceback (most recent call last):
 [Mon Jan 30 13:50:09.497447 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/django/core/handlers/base.py", line 132, in get_response
 [Mon Jan 30 13:50:09.497452 2017] [wsgi:error] [pid 11554:tid 140090457696000] response = wrapped_callback(request, *callback_args, **callback_kwargs)
 [Mon Jan 30 13:50:09.497471 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/django/views/decorators/debug.py", line 76, in sensitive_post_parameters_wrapper
 [Mon Jan 30 13:50:09.497476 2017] [wsgi:error] [pid 11554:tid 140090457696000] return view(request, *args, **kwargs)
 [Mon Jan 30 13:50:09.497481 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/django/utils/decorators.py", line 110, in _wrapped_view
 [Mon Jan 30 13:50:09.497486 2017] [wsgi:error] [pid 11554:tid 140090457696000] response = view_func(request, *args, **kwargs)
 [Mon Jan 30 13:50:09.497490 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/django/views/decorators/cache.py", line 57, in _wrapped_view_func
 [Mon Jan 30 13:50:09.497495 2017] [wsgi:error] [pid 11554:tid 140090457696000] response = view_func(request, *args, **kwargs)
 [Mon Jan 30 13:50:09.497500 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/openstack_auth/views.py", line 102, in login
 [Mon Jan 30 13:50:09.497504 2017] [wsgi:error] [pid 11554:tid 140090457696000] **kwargs)
 [Mon Jan 30 13:50:09.497508 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/django/views/decorators/debug.py", line 76, in sensitive_post_parameters_wrapper
 [Mon Jan 30 13:50:09.497513 2017] [wsgi:error] [pid 11554:tid 140090457696000] return view(request, *args, **kwargs)
 [Mon Jan 30 13:50:09.497517 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/django/utils/decorators.py", line 110, in _wrapped_view
 [Mon Jan 30 13:50:09.497522 2017] [wsgi:error] [pid 11554:tid 140090457696000] response = view_func(request, *args, **kwargs)
 [Mon Jan 30 13:50:09.497526 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/django/views/decorators/cache.py", line 57, in _wrapped_view_func
 [Mon Jan 30 13:50:09.497531 2017] [wsgi:error] [pid 11554:tid 140090457696000] response = view_func(request, *args, **kwargs)
 [Mon Jan 30 13:50:09.497535 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/django/contrib/auth/views.py", line 55, in login
 [Mon Jan 30 13:50:09.497540 2017] [wsgi:error] [pid 11554:tid 140090457696000] form = authentication_form(request)
 [Mon Jan 30 13:50:09.497544 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/django/utils/functional.py", line 16, in _curried
 [Mon Jan 30 13:50:09.497548 2017] [wsgi:error] [pid 11554:tid 140090457696000] return _curried_func(*(args + moreargs), **dict(kwargs, **morekwargs))
 [Mon Jan 30 13:50:09.497553 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/openstack_auth/forms.py", line 71, in __init__
 [Mon Jan 30 13:50:09.497557 2017] [wsgi:error] [pid 11554:tid 140090457696000] self.fields['region'].choices = self.get_region_choices()
 [Mon Jan 30 13:50:09.497562 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/openstack_auth/forms.py", line 101, in get_region_choices
 [Mon Jan 30 13:50:09.497566 2017] [wsgi:error] [pid 11554:tid 140090457696000] default_region = (settings.OPENSTACK_KEYSTONE_URL, "Default Region")
 [Mon Jan 30 13:50:09.497571 2017] [wsgi:error] [pid 11554:tid 140090457696000] File "/openstack/venvs/horizon-master/lib/python2.7/site-packages/django/conf/__init__.py", line 49, in __getattr__
 [Mon Jan 30 13:50:09.497575 2017] [wsgi:error] [pid 11554:tid 140090457696000] return getattr(self._wrapped, name)
 [Mon Jan 30 13:50:09.497588 2017] [wsgi:error] [pid 11554:tid 140090457696000] AttributeError: 'Settings' object has no attribute 'OPENSTACK_KEYSTONE_URL'