local variable 'oauth_provider_name' referenced before assignment

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facebook and twitter sign-in give the following error:

"local variable 'oauth_provider_name' referenced before assignment"

full trace below:

    UnboundLocalError: local variable 'oauth_provider_name' referenced before assignment
/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py TIME: 2013-03-12 10:03:58,558 MSG: base.py:handle_uncaught_exception:215 Internal Server Error: /account/signin/complete-oauth2/
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py", line 111, in get_response
    response = callback(request, *callback_args, **callback_kwargs)
  File "/usr/local/lib/python2.7/dist-packages/askbot/deps/django_authopenid/views.py", line 281, in complete_oauth2_signin
    if csrf_token is None or csrf_token != request.session.pop('oauth2_csrf_token'):
  File "/usr/local/lib/python2.7/dist-packages/django/contrib/sessions/backends/base.py", line 54, in pop
    return self._session.pop(key, *args)
KeyError: 'oauth2_csrf_token'

i have tried the following already:

1. syncing the time, and clearing cache and cookies on the client machine, but error persists.
2. I have memcached on the server. cleared that as well. Restarted apache. Error persists
3. Yahoo and Google Sign-Ins are working fine. FB and twitter were also working till recently.