> The attached test script demonstrates the issue on Python 2.6 and 3.2, and code inspection suggests this is still valid for 2.7 and 3.4.

I disagree that Python 3.4 is affected: RLock has been reimplemented in C in Python 3.2. Only the Python implementation of RLock has the bug, but it's not used by fault, you have to explicitly use a private attribute of the threading module to get it.

Python 2.6 only accept security fixes, so in fact only Python 2.7 may get a fix.

The question is if it worth to backport 300 lines of C code from Python 3 to Python 2 in the _thread module.

@Benjamin, release manager of Pythn 2.7: What do you think? I may help to backport the C implementation of RLock.