This required an option to be added to NullRegionData via ConnectionString for it to act as a non-static instance, so that regression tests (which only load this class once) don't get hopeless confused and complex to compensate.
Normal standalone operation unaffected.
This is not used for anything - appearances are always properties of objects with ids (ScenePresence, AgentCircuitData) and just has the potential to get out of sync when the appearance is cloned.
Justin Clark-Casey (justincc)