Comment 2 for bug 1864110

Reviewed: https://review.opendev.org/708746
Committed: https://git.openstack.org/cgit/starlingx/root/commit/?id=9b77e2e1b346c7f2f6fe617bc9c48e3c9c39d6de
Submitter: Zuul
Branch: master

commit 9b77e2e1b346c7f2f6fe617bc9c48e3c9c39d6de
Author: Scott Little <email address hidden>
Date: Mon Oct 28 19:22:57 2019 -0400

    Build avoidance fixes

    1) Build avoidance fails on a clean workspace because directory
    $MY_WORKSPACE/tmp doesn't exist when mktemp needs to
    create a forth subdir under that path.

    Add a 'mkdir -p $MY_WORKSPACE/tmp' to ensure it exists
    prior to mktemp.

    2) Failed to rebuild kmods after a kernel change and
    building with build-avoidance enabled. The problem was
    a missing dependency cache that would have listed
    the kmods as having dependencies on the kernel.
    Reusing kmods from a prior build in conjunction with
    a rebuilt kernel results int load with unusable kmods
    due to a key mismatch.

    Add the dependancy-cache to the list of artifacts to
    syncronize as part of build avoidance. A primed
    dependency cache will allow build-pkgs to determine
    that kmods must be rebuilt when the kernel has changed.

    3) Make sure $MY_WORKSPACE/$BUILD_TYPE/repo
    symlink exists after a build avoidance build.
    If no packages require a rebuild, it was missing.

    4) Fix an error message that was puzzling while debugging
    the above issues.

    Closes-Bug: 1864110
    Change-Id: Ia912b2e3e110efbe69004d7978109ebb089d684b
    Signed-off-by: Scott Little <email address hidden>