Comment 4 for bug 1797966

Reviewed: https://review.opendev.org/610727
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=6c3e8bc48e460c96f4fc8d975a63ef76e6f55694
Submitter: Zuul
Branch: master

commit 6c3e8bc48e460c96f4fc8d975a63ef76e6f55694
Author: Matt Riedemann <email address hidden>
Date: Mon Oct 15 16:45:14 2018 -0400

    libvirt: don't log error if guest gone during interface detach

    Similar to change I8ae352ff3eeb760c97d1a6fa9d7a59e881d7aea1, if
    we're processing a network-vif-deleted event while an instance
    is being deleted, the asynchronous interface detach could fail
    because the guest is gone from the hypervisor. The existing code
    for handling this case was using a stale guest object so this
    change tries to refresh the guest from the hypervisor and if the
    guest is gone, the Host.get_guest() method should raise an
    InstanceNotFound exception which we just trap, log and return.

    Change-Id: Ic4c870cc5078d3f7ac6b2f96f8904c2a47de418e
    Closes-Bug: #1797966