Updated openstack/openstack
Project: openstack/taskflow  a440ec40a518f8ee25ba5a945847e5b4eefdb45c

Add a moved_inheritable_class deprecation helper

For cases where inheritance is still needed we should provide
a mechanism to provide this so that consuming users of the
library can still refer to the old location for a period of time
so that there derived code does not fail due to the movement
of the class that occurred.

Change-Id: I8cd5b707125264f6b595d5b3ac327cfe16e7923c