Comment 24 for bug 1586931

Reviewed: https://review.openstack.org/358153
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=daf281f95fa96aef72933280d873112b5e72807c
Submitter: Jenkins
Branch: stable/mitaka

commit daf281f95fa96aef72933280d873112b5e72807c
Author: Ken'ichi Ohmichi <email address hidden>
Date: Fri Aug 12 10:15:29 2016 -0700

    Return None in get_instance_id_by_floating_address

    _show_port() can raise a PortNotFound exception, but the method
    get_instance_id_by_floating_address() doesn't handle it. On the
    other hand, the method returns None if fip doesn't contain
    port_id as a normal case.
    On the caller side, "Delete a floating ip" API can use the returned
    value None to disassociate_and_release_floating_ip() and the method
    handles the None as a normal value.

    So this patch makes get_instance_id_by_floating_address return None
    if PortNotFound happens.

    Closes-Bug: #1586931

    Change-Id: I03be8100155d343eb6a4ea9eda3f1498ad3fb4cf
    (cherry picked from commit e72826123bfd7c1d962b615da3f028b315ba3943)