I believe that the implementation of Condition._is_owned is wrong, as mentioned here: https://mail.python.org/pipermail/python-list/2012-October/632682.html.  Specifically, the two return values (True and False) should be inverted.

I guess this slipped through as this private function would only be called if one passed to a Condition object a (R)Lock-like object that doesn't define _is_owned.  (I noticed this when I tried to pass a custom-written reader-writer lock to a Condition object.)  Technically, the docs says that "If the lock argument is given and not None, it must be a Lock or RLock object", but in practice anything that defines acquire(), release() (and possibly _is_owned()) should work.