Revoke a user from the tenant
            This will remove pending or approved roles but
            will not not delete the user from Keystone.

def revoke_user(self, user_id):
        """ Revoke a user from the tenant
            This will remove pending or approved roles but
            will not not delete the user from Keystone.
        """

        uri = 'openstack/users/%s' % user_id
        try:
            resp = self.delete(uri)
        except AttributeError:
            # note: this breaks. stacktask returns a string, not json.
            return
        self.expected_success(200, resp.status)
        return rest_client.ResponseBody(resp, None)