¿Cómo arreglar el error 403 de python-social-auth con Google?

Si tiene el siguiente error cuando trata de autenticarse con la cuenta de Google

ERROR 2014-05-29 21:25:06,289 base :: Internal Server Error: /social/complete/google-oauth2/
Traceback (most recent call last):
  File "/Users/vera/.virtualenvs/activar/lib/python2.7/site-packages/django/core/handlers/base.py", line 111, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/Users/vera/.virtualenvs/activar/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 57, in wrapped_view
    return view_func(*args, **kwargs)
  File "/Users/vera/.virtualenvs/activar/lib/python2.7/site-packages/social/apps/django_app/utils.py", line 45, in wrapper
    return func(request, backend, *args, **kwargs)
  File "/Users/vera/.virtualenvs/activar/lib/python2.7/site-packages/social/apps/django_app/views.py", line 21, in complete
    redirect_name=REDIRECT_FIELD_NAME, *args, **kwargs)
  File "/Users/vera/.virtualenvs/activar/lib/python2.7/site-packages/social/actions.py", line 44, in do_complete
    *args, **kwargs)
  File "/Users/vera/.virtualenvs/activar/lib/python2.7/site-packages/social/strategies/base.py", line 71, in complete
    return self.backend.auth_complete(*args, **kwargs)
  File "/Users/vera/.virtualenvs/activar/lib/python2.7/site-packages/social/backends/oauth.py", line 358, in auth_complete
    *args, **kwargs)
  File "/Users/vera/.virtualenvs/activar/lib/python2.7/site-packages/social/backends/oauth.py", line 362, in do_auth
    data = self.user_data(access_token, *args, **kwargs)
  File "/Users/vera/.virtualenvs/activar/lib/python2.7/site-packages/social/backends/google.py", line 47, in user_data
    params={'access_token': access_token, 'alt': 'json'}
  File "/Users/vera/.virtualenvs/activar/lib/python2.7/site-packages/social/backends/base.py", line 209, in get_json
    return self.request(url, *args, **kwargs).json()
  File "/Users/vera/.virtualenvs/activar/lib/python2.7/site-packages/social/backends/base.py", line 205, in request
    response.raise_for_status()
  File "/Users/vera/.virtualenvs/activar/lib/python2.7/site-packages/requests/models.py", line 795, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
HTTPError: 403 Client Error: Forbidden

se necesita activar Google+ API para su aplicación en 
la consola de Google: