Comment 5 for bug 1903727

Reviewed: https://review.opendev.org/c/openstack/python-glanceclient/+/803326
Committed: https://opendev.org/openstack/python-glanceclient/commit/1eb0bbbed7c5ce12aee5f26be7a7aec51ae9ef55
Submitter: "Zuul (22348)"
Branch: master

commit 1eb0bbbed7c5ce12aee5f26be7a7aec51ae9ef55
Author: Mridula Joshi <email address hidden>
Date: Tue Aug 3 10:35:40 2021 +0000

    Fix undesirable raw Python error

    Using the glanceclient without a subcommand while
    passing an optional argument triggers the raw Python
    error `ERROR: 'Namespace' object has no attribute
    'func'`. This bug can be reproduced by issuing the
    command `glance --os-image-api-version 2`.
    Added a default value to `func` as placeholder
    so that a help message is shown instead of the Python error.

    Closes-Bug: #1903727
    Change-Id: Ie4288262e408192310cbbc240bd1779b265a64fd