Comment 5 for bug 1897760

Reviewed: https://review.opendev.org/755064
Committed: https://git.openstack.org/cgit/openstack/tripleo-heat-templates/commit/?id=0f7ed0b8d521ad7e9333482e59894af210d63d03
Submitter: Zuul
Branch: master

commit 0f7ed0b8d521ad7e9333482e59894af210d63d03
Author: Sergii Golovatiuk <email address hidden>
Date: Tue Sep 29 17:17:44 2020 +0200

    Default cinder_volume_node_names to []

    There are cases when cinder_volume_node_names is not defined. It was
    fixed for "set cinder_volume upgrade node facts from the limit option"
    task in loop but never for non HA task. So, standalone upgrade job
    fails with the following message.

    "msg": "The task includes an option with an undefined variable. The
    error was: 'cinder_volume_node_names' is undefined\n\nThe error appears
    to be in
    '/home/zuul/standalone-ansible-YpY5Oe/Standalone/upgrade_tasks_step1.yaml':
    line 27, column 5, but may\nbe elsewhere in the file depending on the
    exact syntax problem.\n\nThe offending line appears to be:\n\n- block:\n
    - name: set cinder_volume upgrade node facts in a single-node
    environment\n ^ here\n",

    This patch defaults cinder_volume_node_names to [] when
    cinder_volume_node_names is not defined in hiera.

    Closes-Bug: #1897760

    Change-Id: I1145c39e379ac6579662f2bbfcc9a4d2d3e0f059