Comment 10 for bug 1773765

Reviewed: https://review.opendev.org/753926
Committed: https://git.openstack.org/cgit/openstack/masakari/commit/?id=e0423906a7aabb4ea02b754e041f725c16535be5
Submitter: Zuul
Branch: stable/train

commit e0423906a7aabb4ea02b754e041f725c16535be5
Author: suzhengwei <sugar-2008@163.com>
Date: Fri Apr 17 08:59:35 2020 +0800

    check expired notifications

    Occasionally, there would be notifications which will remain 'new',
    'error' or 'running' status all times, and not to be processed again.
    Due to this, operator can not update the segment or host.

    This patch add one task to periodically check unfinished notifications.
    If one unfinished notification is expired, just set its status to
    'failed'.

    Conflicts:
            masakari/tests/unit/engine/test_engine_mgr.py
            - Update test for difference of unittest.mock and mock

    Closes-Bug: #1773765
    Change-Id: If49635639dd976aeec3ea73e702ad2636fcf1e0a
    (cherry picked from commit 3a4f782441f6bdcfb8ee49a393937267fc246c56)