Ha! Already gave them my analysis, and stopped using that package since.
While I certainly think this is not the trivial, basic usage, and that the pattern used for the lock is common (and part of some PEP if I remember correctly), I'm kind of puzzled on that fact that context manager solves it. 
The test will pass constantly once the change is made (even though it looks like RLock __enter__ is just calling the acquire function), and I overall think this is a good change to do in the Handler class, even it's just for self.lock (can we find and understand why the last proposal was rejected?).

I'll submit a PR in a few days, but was wondering on the usage of the lock, and that it doesn't always exists on `self`. Anyway, I assume these are questions that we can continue discussing in the PR if you also think this is a good direction..