Fix uninstall

[sambrightman]

• don't fail if already uninstalled
• remove both shims
• unset current
• complete tests

[sambrightman]

@rejeep are you happy for me to proceed with PRs like this (as opposed to only committing new release versions)?

[sambrightman]

Since you've approved, I'll merge. If you intended to request changes before merging yourself let me know.

My thinking was actually the opposite of yours! "Test for the effects you want to see rather than how they are achieved". The fact that disuse is called is an internal implementation detail - the existing method could have been modified to do the two missing steps without calling disuse, and the test would not have to know.

[rejeep]

This way, if you change the definition of disuse! you also have to update lots of other non related tests. But let's agree to disagree, do as you please, not that big of a deal. 🙂