Comment 7 for bug 1782404

Reviewed: https://review.openstack.org/583698
Committed: https://git.openstack.org/cgit/openstack/keystonemiddleware/commit/?id=3fc10b237affb9614a6591f494ab7e8490b81cce
Submitter: Zuul
Branch: stable/queens

commit 3fc10b237affb9614a6591f494ab7e8490b81cce
Author: Morgan Fainberg <email address hidden>
Date: Wed Jul 18 11:26:18 2018 -0700

    Fix KeystoneMiddleware memcachepool abstraction

    Keystonemiddleware's abstraction for the memcache pool was broken
    when converting to use a queue.Queue. The logic that placed the
    connection back into the pool was moved to .acquire and the reserve
    method was not using acquire.

    Conflicts:
        keystonemiddleware/auth_token/_cache.py
        keystonemiddleware/tests/unit/auth_token/test_cache.py

    Change-Id: I0eda5981cbb661f63790258cf8e70c7340615159
    Closes-Bug: #1782404
    (cherry picked from commit dea1e94d6c89b5df630f30cf61464ed67d5d1ab0)