SpoutDev/Spout — comment on commit a8771fac7098f2322cebfcaef3ee02c84e295f2a
File: src/main/java/org/spout/server/entity/SpoutEntity.java line 126
By Afforess:

Without this line and L136, the entity tracking will become garbage. Regions use the controller as a key in the entity manager and need to be informed of the change:

https://github.com/SpoutDev/Spout/blob/master/src/main/java/org/spout/server/entity/EntityManager.java#L64