Git commits in Moodle 3.2.x by Fred Woolard

commit c4bb09b7421a23397a6ddd68f0a25070769b64cb
Author: Fred Woolard <woolardfa@appstate.edu>
Date:   Tue, 24 Oct 2017 01:22:42 +0800
Tag:    v3.2.6

MDL-57477 core: If memcached 3.x mimic 2.2.0 lock acquisition behavior