Sync from oslo-incubator.
Sync from oslo-incubator.

Change-Id: I3a7c6bdfae9f2273cf8059c322d648cda07d830d
Reviewed-on: https://review.openstack.org/28619
Reviewed-by: Clark Boylan <635fc31d01fa593720982fa0568e87170cedbe2c@gmail.com>
Approved: Jeremy Stanley <98883b97e35b7bb1ac282bb863f2e9d917db0454@yuggoth.org>
Reviewed-by: Jeremy Stanley <98883b97e35b7bb1ac282bb863f2e9d917db0454@yuggoth.org>
Tested-by: Jenkins

devdattakulkarni/zuul_messaging,gooddata/zuul,wikimedia/integration-zuul,wikimedia/integration-zuul,wikimedia/integration-zuul,gooddata/zuul,gooddata/zuul,gooddata/zuul,wikimedia/integration-zuul,devdattakulkarni/zuul_messaging,devdattakulkarni/zuul_messaging,gooddata/zuul