Hooks added as a side effect of a called function don't get cleaned up

[sarahsturgeon]

The test environment we create keeps track of hooks added with hook.Add and automatically cleans them up after the test completes.

However, if you call a function that calls hook.Add, they will not be tracked.

Is there a clever way of using setfenv (perhaps on a thread instead of a function?) that will let us accomplish this? Or should we just accept the fact that you need to clean up any hooks you indirectly create in your tests?