Comment 14 for bug 1577721

The cause of this bug in "mitaka" (MOS9.0) was refactoring - new code was added:
https://github.com/openstack/neutron/commit/ccdf211b4cf224d415520c7d70b7f53952674414

So, the patches provided in upstream:

https://review.openstack.org/#/c/321131/
https://review.openstack.org/#/c/321131/

solved the issue for "mitaka" and "master".

As MOS8.0 ("liberty") doesn't have this code, hence, an issue with MOS8.0 can be caused
by another problems that are not relevant to this bug and provided in upstream patch
can't be backported to MOS8.0