Comment 5 for bug 1884094

Reviewed: https://review.opendev.org/737403
Committed: https://git.openstack.org/cgit/starlingx/update/commit/?id=d3f8af4f4c6df5eede6f83d67bff8970d4bd1ed7
Submitter: Zuul
Branch: master

commit d3f8af4f4c6df5eede6f83d67bff8970d4bd1ed7
Author: Don Penney <email address hidden>
Date: Mon Jun 22 21:16:35 2020 -0400

    Protect against stale repo data in DNF cache

    When the patch-agent is notified by the patch-controller of a new
    patching operation (patch_op_counter in HELLO is incremented), it will
    run a new software query consisting first of running "dnf makecache",
    then checking the software repositories for changes. In rare cases,
    the metadata returned to dnf when it makes the query could be stale,
    resulting in the patch-agent believing the current software is
    up-to-date.

    In order to protect against this, the patch-agent will now verify the
    repository revision id for the updates repo. If the revision id has
    not changed when it is reasonable to expect it could have (ie. the
    patch_op_counter has increased, indicating the repository may have
    been updated), the patch-agent will retry once to allow for any
    potential caching to have cleared.

    Change-Id: I3a44ed86e16cd9fe67f0b0e763c95a5a7e126cf8
    Closes-Bug: 1884094
    Signed-off-by: Don Penney <email address hidden>