Comment 2 for bug 1723639

Reviewed: https://review.openstack.org/512035
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=14b0451fc9ebfd8e775b2aa9c8feac31e456a9ad
Submitter: Zuul
Branch: master

commit 14b0451fc9ebfd8e775b2aa9c8feac31e456a9ad
Author: Dan Prince <email address hidden>
Date: Mon Oct 16 16:18:44 2017 -0400

    Move FakeKeystoneClient to engine.clients

    Add the ability to consume FakeKeystoneClient class as a client
    module. This avoids extra dependencies on the Python mox/mox3
    libraries at runtime and allows the end user to wire in the
    custom class by simply making the following config setting:

      keystone_backend = heat.engine.clients.os.keystone.fake_keystoneclient.FakeKeystoneClient

    This use case for this is the TripleO undercloud installer which
    uses a heat-all process to transform heat templates into Ansible
    playbooks. Previously we leveraged a "fake_keystone" service
    as multiple applications and binaries required keystone dependencies.
    (Both Heat, os-collect-config, and some openstackclients wanted
     a fully version of keystone running)

    Now that we've streamlined these dependencies allowing heat to use
    a fake KeystoneClient library shim instead of the full fake_keystone
    process is much lighter and avoids the security concerns of the extra
    socket. This patch allows us to do all of this without installing extra
    test time dependencies on mox/mox3.

    Change-Id: I03f1789957ba157871fd13164592116d7fcdabe4
    Closes-bug: #1723639