Comment 3 for bug 1759979

Reviewed: https://review.openstack.org/564468
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=ffe092b112884fda2420ee847128ed975686e8cb
Submitter: Zuul
Branch: stable/queens

commit ffe092b112884fda2420ee847128ed975686e8cb
Author: Matt Riedemann <email address hidden>
Date: Thu Apr 19 17:42:23 2018 -0400

    xenapi: handle InstanceNotFound in detach_interface()

    CI tests frequently teardown by rolling back interface
    attachments and then deleting the server, both of which
    are asynchronous. If we're trying to detach an interface
    on a guest that is gone, we don't need to log a traceback
    exception in the logs, just let the InstanceNotFound
    raise up to the ComputeManager which will handle the
    error and log it appropriately.

    Change-Id: I9428be0e6e5b640fdda00410817925001361fd2c
    Closes-Bug: #1759979
    (cherry picked from commit 5a42701f89a5139acdc38f8572b1083ba528264c)