Comment 8 for bug 1741223

Reviewed: https://review.openstack.org/531120
Committed: https://git.openstack.org/cgit/openstack/ironic/commit/?id=2b5849b49e24f310b7cf7f7c2e9a8b14f11da2a7
Submitter: Zuul
Branch: master

commit 2b5849b49e24f310b7cf7f7c2e9a8b14f11da2a7
Author: Dmitry Tantsur <email address hidden>
Date: Thu Jan 4 11:10:18 2018 +0100

    Rework exception handling on deploy failures in conductor

    Currently on unexpected python error we only log the error message, e.g.
    "NoneType object is not iterable" or just KeyError missing key. This is
    obviously not helping debugging too much.

    This change splits error handling into separate handling of IronicException
    and other exceptions.

    For IronicException: only log the error message, remove redundant "Error: "
    from the last_error message.

    For other exceptions: log traceback, mention that the exception was not
    expected.

    Finally, move logging to the top of the error handling helper to make sure
    it never gets lost.

    Change-Id: Idc2339c3bdad8092907d9651d40f241a2ae50dbe
    Related-Bug: #1741223