Updated openstack/openstack
Project: openstack/keystone  2b8f25bd35afa693ebb5135a491f84d5b87a564a
null
Fixes bug in exception message generation

When an invalid dogpile memcache backend was specified the resulting
ValueError message didn't contain the invalid backend properly.

This patch fixes the issue and adds a test to show the expected
behavior.

Change-Id: Ib9efee59e3839230034da95e48e47356c65b2fdb