Repro:
https://gist.github.com/dcomartin/a631b002ce761ac5d64d77ab38c705e8
This is also the case with using the RegisterType with the obsolete InjectionFactory. However, this is a change of behavior because InjectionFactory used to give you the container/child that was doing the resolution of the outer type. I've confirmed that was the behavior back in at least version 5.8.13.