adopt oslo_config.fixture.Config

[Ihar Hrachyshka]

Currently, base test class tries to mock out oslo.config autodiscovery to isolate tests from external configuration files, but does not make it completely. F.e. policy.d directory is still accessed by oslo.policy code, making bugs like bug 1484553.

I hope that adopting the fixture should isolate us from all configuration files that are external to unit tests tree.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/254301

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sergey Belous (<email address hidden>) on branch: master
Review: https://review.openstack.org/254301
Reason: Not sure that it make sense

[Armando Migliaccio (armando-migliaccio)]

This bug is > 180 days without activity. We are unsetting assignee and milestone and setting status to Incomplete in order to allow its expiry in 60 days.

If the bug is still valid, then update the bug status.

[Launchpad Janitor (janitor)]

[Expired for neutron because there has been no activity for 60 days.]