Comment 4 for bug 1839674

Reviewed: https://review.opendev.org/675704
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=f578146f372386e1889561cba33e95495e66ce97
Submitter: Zuul
Branch: master

commit f578146f372386e1889561cba33e95495e66ce97
Author: Matt Riedemann <email address hidden>
Date: Fri Aug 9 17:17:45 2019 -0400

    rt: only map compute node if we created it

    If ComputeNode.create() fails, the update_available_resource
    periodic will not try to create it again because it will be
    mapped in the compute_nodes dict and _init_compute_node will
    return early but trying to save changes to that ComputeNode
    object later will fail because there is no id on the object,
    since we failed to create it in the DB.

    This simply reverses the logic such that we only map the
    compute node if we successfully created it.

    Some existing _init_compute_node testing had to be changed
    since it relied on the order of when the ComputeNode object
    is created and put into the compute_nodes dict in order
    to pass the object along to some much lower-level PCI
    tracker code, which was arguably mocking too deep for a unit
    test. That is changed to avoid the low-level mocking and
    assertions and just assert that _setup_pci_tracker is called
    as expected.

    Change-Id: I9fa1d509a3de405d6246fb8670612c65c10cc93b
    Closes-Bug: #1839674