Bagpipe driver: test Neutron registry callbacks

[Thomas Morin]

We need a test to detect any possible change in the signatures of Neutron registry callbacks.

The test would load ML2, create a port and check that the bagpipe driver callbacks are called with the expected signatures.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/249081

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/249081
Committed: https://git.openstack.org/cgit/openstack/networking-bgpvpn/commit/?id=2aebe3da2d16578574ab8f8c2a86aeafdd16c0ca
Submitter: Jenkins
Branch: master

commit 2aebe3da2d16578574ab8f8c2a86aeafdd16c0ca
Author: Thomas Morin <email address hidden>
Date: Tue Nov 24 09:51:47 2015 +0100

    bagpipe: port delete action on BEFORE_DELETE event

    Details on the issue in bug #1517480.

    We need to subscribe to port before_delete events, because
    on after_delete events the port is already removed from the db
    and we can't retrieve the binding:host_id information (which
    is not passed in the event either).

    This change also include a unit test against this bug, which also
    happens to go through the ML2 RPC-to-registry codepaths so that
    the effect of real registry events against our code are tested, thus
    testing the validity of the expectation that the bagpipe driver code
    has against ML2. This addresses bug #1493901.

    One test is not passing, and thus commented out: see bug 1519258.

    Closes-Bug: 1517480
    Closes-Bug: 1493901

    Change-Id: Icce89d98bcc4424529dcbe661fed3c1c8191418c

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: backport/kilo
Review: https://review.openstack.org/251780