Update security group failed with the same stateful data

[lina He]

With the merge of the stateless support patchset(https://review.opendev.org/#/c/572767/48).

We found a failing scenario that the stateful configuration can't be updated when updating with the same stateful configuration.

To reproduce:
- Create a security group with stateful False(True)
- Add this security group to the port
- Update the security group to be stateful False(True)

The update will fail because the security group is used by the port.

The security groups should be updatable with the same stateful data.

[lina He (linahe)]

Fix proposed to master branch:
Review: https://review.opendev.org/#/c/711385/1

The corresponding tests will be added later.

[Bence Romsics (bence-romsics)]

This bug can be reproduced independently of the backend supporting stateless security groups. I agree that noop updates should be accepted.

Thank you for the bug report and the fix.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/711385
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=2b56e60140dd07f24fd8f1adf08ae8b213cea4ca
Submitter: Zuul
Branch: master

commit 2b56e60140dd07f24fd8f1adf08ae8b213cea4ca
Author: Lina He <email address hidden>
Date: Thu Mar 5 06:07:29 2020 +0000

    Unblock security group update with same stateful data

    Closes-Bug: #1866160
    Blueprint: stateless-security-groups

    Change-Id: I46d80a2a4f114a6775827ab3caa61dee9f5f1361