update tenant api changed

It used to return an 'extra' item in its response.

    def test_tenant_update_desc(self):
        """Update description attribute of a tenant"""
        t_name = rand_name('tenant-')
        t_desc = rand_name('desc-')
        resp, body = self.client.create_tenant(t_name, description=t_desc)
        t_id = body['id']
        resp1_desc = body['description']

        t_desc2 = rand_name('desc2-')
        resp, body = self.client.update_tenant(t_id, description=t_desc2)
        st2 = resp['status']
        print body
        resp2_desc = body['extra']['description']
        self.assertTrue(st2.startswith('2'))
        self.assertNotEqual(resp1_desc, resp2_desc)

        resp, body = self.client.get_tenant(t_id)
        resp3_desc = body['description']

        self.assertNotEqual(resp1_desc, resp3_desc)
        self.assertEqual(t_desc, resp1_desc)
        self.assertEqual(resp2_desc, resp3_desc)

        self.client.delete_tenant(t_id)

Update description attribute of a tenant ... {u'id': u'77e37eb480b642ca99e54c8f8e22c23d', u'enabled': u'true', u'description': u'desc2-500469', u'name': u'tenant-669507'}
ERROR

======================================================================
ERROR: Update description attribute of a tenant
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/stack/tempest/tempest/tests/identity/admin/test_tenants.py", line 218, in test_tenant_update_desc
    resp2_desc = body['extra']['description']
KeyError: 'extra'