---
upgrade:
  - |
     Default value of config option ``CONF.placement.region`` is updated
     from ``RegionOne`` to empty string.

     As per tempest design, if tempest conf is not having any region for
     a service then identity region should be used. In case of placement
     the default value is "RegionOne" which is considered as placement
     region if region missing in tempest conf. In order to have identity
     region to be used as default we need to change to empty string for
     placement service. Empty string can be seen being used in other
     services like volume, image etc.