Comment 9 for bug 1501873

Reviewed: https://review.openstack.org/273236
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=05de3183a3a85a08d8ea4cfcd87cefa8b67ceb4b
Submitter: Jenkins
Branch: stable/liberty

commit 05de3183a3a85a08d8ea4cfcd87cefa8b67ceb4b
Author: Swaminathan Vasudevan <email address hidden>
Date: Thu Oct 1 11:48:55 2015 -0700

    Delete fipnamespace when external net removed on DVR

    The fipnamespace is associated with an external network
    on a given node. In the case of DVR there is just one
    single FIP namespace for a given node.

    We have seen some race conditions in the agent for creation
    and deletion of the fip namespace. See the bug report for
    details on the failure.

    So in order to address this race condition and make the
    code more stable, we will be cleaning up the fip namespace
    only when an external network is removed.

    The server will be sending a rpc notification message to
    the agent to cleanup the fip namespace when the external
    net is removed.

    This patch address the above mentioned issue by not constantly
    deleting and creating the fip namespace.

    Conflicts:
     neutron/tests/functional/agent/test_l3_agent.py

    Closes-Bug: #1501873
    (cherry picked from commit cb465d40f59bfbc109204dc16259c0e4ce1c903a)
    Change-Id: I86869f66d4afffad7db09942578b1a456a9bd418