Flacky unit test with py36

[Gustavo Sanchez]

Sometimes unit test TestManilaCharm.test_install() in test_lib_charm_openstack_manila.py passes and sometimes it throws an error after mocking using charms_openstack.test_utils.PatchHelper.patch()

The problem is just present in py36 unit tests

https://pastebin.canonical.com/p/pDxq5X5qfy/

Problem seems to be trying to mock super().install() of class ManilaCharm(charms_openstack.charm.HAOpenStackCharm)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/charm-manila/+/805405

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/charm-manila/+/805405
Committed: https://opendev.org/openstack/charm-manila/commit/310647c2bd3010f0ae9096e396d21402d20a95bf
Submitter: "Zuul (22348)"
Branch: master

commit 310647c2bd3010f0ae9096e396d21402d20a95bf
Author: Gustavo Sanchez <email address hidden>
Date: Fri Aug 20 10:41:53 2021 -0400

    Fixes flacky unit test wih py36

    When running TestManilaCharm.test_install() with py36 sometimes
    test passes and sometimes throws and error while mocking methods.
    Seems to be an async race problem mocking a super method first.

    This was solved by avoiding mocking super method first.

    Closes-Bug: #1940552
    Change-Id: Iac55321599b4866784a0631639a93fc828780647