Comment 9 for bug 1554825

Reviewed: https://review.openstack.org/321628
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=59236a014859e1e14a5844286903753d3f520e3e
Submitter: Jenkins
Branch: stable/liberty

commit 59236a014859e1e14a5844286903753d3f520e3e
Author: Shih-Hao Li <email address hidden>
Date: Fri Mar 11 15:13:34 2016 -0800

    Update network object in DHCP agent with router interface changes

    In Dnsmasq, the function get_isolated_subnets() returns a list of
    subnets in a network if the subnet is not connected to a router.

    The implementation of this function checks all the router interface
    ports in a cached network object passed from DHCP agent. But the
    cached network object is not updated when a subnet is attached to
    or detached from a router.

    This patch fixes that by adding callback functions in DHCP RPC client
    to notify DHCP agent when changes happen on router interfaces.

    Conflicts:
     neutron/api/rpc/agentnotifiers/dhcp_rpc_agent_api.py
     neutron/db/l3_db.py
     neutron/db/l3_dvr_db.py

    Local changes:
    - in a unit test, moved callback failure setup to after interface is
      added to a router, because now we call to register.notify in
      add_router_interface too, and the test intends to trigger failure mode
      for interface removal only.

    Closes-Bug: #1554825
    Change-Id: Ifaab163f49e0d1c5cb3eba6efa96214104647e4e
    (cherry picked from commit aa00310eef0d2507c4da76eb5dd5130df043b0a5)