Wow, that was quick. Did you try to replace threading.RLock with your
implementation, and run the tests?

By the way:
> - acquire() method argument "blocking" is not a keyword
> - In the Python version, RLock._release_save() replaces owner and 
> counter attributes before release the lock. But releasing the lock may 
> fails and no the object is in an inconsistent state

Removing the debugging statements is fine, but apart from that the C
implementation should mimick the current behaviour. Even if this
behaviour has potential pitfalls.

Speaking of which, it would be nice if RLock was subclassable. I don't
know whether any software relies on this though.