Comment 4 for bug 1813014

Reviewed: https://review.openstack.org/639928
Committed: https://git.openstack.org/cgit/openstack/tripleo-heat-templates/commit/?id=e5d6b52c15349f88788f8fea42071ec9fd5dba5c
Submitter: Zuul
Branch: stable/rocky

commit e5d6b52c15349f88788f8fea42071ec9fd5dba5c
Author: Michele Baldessari <email address hidden>
Date: Wed Jan 23 14:10:41 2019 +0100

    Fix nova_cell_v2_discover_host.py with python3

    When this script runs via python3 it fails with:

      "stdout: ",
      "stderr: + command -v python3",
      "+ python3 /docker-config-scripts/nova_cell_v2_discover_host.py",
      "Traceback (most recent call last):",
      " File \"/docker-config-scripts/nova_cell_v2_discover_host.py\", line 75, in <module>",
      " TypeError: a bytes-like object is required, not 'str'"

    This is because in python3 subprocess.check_output() will return bytes
    and trying to split it using a string '\n' will break with the error
    above. Let's just use the universal_newlines=True parameter which we
    have been using everywhere in tripleo so far.
    Also skip any empty lines that might show up in the output which would
    give the error:

      ValueError: not enough values to unpack (expected 2, got 0)

    Tested with a python3 deployment and got a successful deployment (rhel8
    os + f28 based-containers).

    Change-Id: Ic7904c4f3027cc5e7e05d52757e36dbc05f3d487
    Co-Authored-By: Damien Ciabrini <email address hidden>
    Closes-Bug: #1813014
    (cherry picked from commit 87a869a408b9732e9ff46e8fecfa1487b3699ffa)