Problem / Motivation
In trying to test the changes documented in [#2170437], the simple registration of a config.module.overrides event seems to have no effect. The getSubscribedEvents() method fires, but the registered method is never called.
The test code is here: https://github.com/agentrickard/domain/tree/8.0.x/domain_config and contains simpletests.
There are, granted, a lot of moving parts here, so it may be a case of connecting all the dots.
But the current tests for this behavior in core are only unit tests, so far as I can tell, so we have no proper integration tests for the config override system. In contrib, they simply seem to fail.