Comment 4 for bug 1856902

Reviewed: https://review.opendev.org/699997
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=40950f9c87681a1db0f3819530dd0b89ac5f6553
Submitter: Zuul
Branch: master

commit 40950f9c87681a1db0f3819530dd0b89ac5f6553
Author: Matt Riedemann <email address hidden>
Date: Thu Dec 19 09:41:18 2019 -0500

    Fix race in test_create_servers_with_vpmem

    This test creates 2 servers which take up all of the
    CUSTOM_PMEM_NAMESPACE_SMALL resources on the sole host in
    the test. Then it tries to create a 3rd server which it
    expects to fail and it does. Then it deletes the second
    server to free up one CUSTOM_PMEM_NAMESPACE_SMALL resource
    on the host and schedules another server which it expects
    to work. The problem is the test doesn't wait for the
    second server to be fully deleted so the test intermittently
    fails when the CUSTOM_PMEM_NAMESPACE_SMALL resource isn't
    yet freed up when the fourth server goes through scheduling.

    This adds a simple wait call for the deleted server to actually
    be gone before creating the fourth server.

    Change-Id: Id3389038b5fed1e70dd12c7ed9cef2c0950625cf
    Closes-Bug: #1856902