'GET /users (unprotected).
Test Plan:
- Update policy so api is unprotected
- Use an un-scoped token to make sure we can get back all
the users independent of domain'

def test_list_users_unprotected(self):

    self._set_policy({'identity:list_users': []})
    r = self.get('/users', auth=self.auth)
    id_list = self._get_id_list_from_ref_list(r.result.get('users'))
    self.assertIn(self.user1['id'], id_list)
    self.assertIn(self.user2['id'], id_list)
    self.assertIn(self.user3['id'], id_list)
