(tested on python 2.7)

Created a threading.Condition(threading.RLock())
A piece of code acquires the lock using a with block and waits (for a notify)
While wait() is running a KeyboardInterrupt is raised
An exception is raised while exiting the lock's with block:
  File "/usr/lib/python2.7/threading.py", line 289, in __exit__
    return self.__lock.__exit__(*args)
  File "/usr/lib/python2.7/threading.py", line 216, in __exit__
    self.release()
  File "/usr/lib/python2.7/threading.py", line 204, in release
    raise RuntimeError("cannot release un-acquired lock")

example code running on the main thread:
def waiting(lock): # (the lock was created using Condition(RLock()))
  with lock:
    lock.wait(timeout=xxx) # while waiting a keyboard interrupt is raised

The issue is caused because threading.RLock doesn't handle the exception correctly:
    def _acquire_restore(self, count_owner):
        count, owner = count_owner
        self.__block.acquire()
        self.__count = count
        self.__owner = owner
        if __debug__:
            self._note("%s._acquire_restore()", self)

The exception is raised after the acquire() returns and the count and owner are not restored.

The problem was solved using the following fix (added try, finally):
    def _acquire_restore(self, count_owner):
        count, owner = count_owner
        try:
            self.__block.acquire()
        finally:
            self.__count = count
            self.__owner = owner
            if __debug__:
                self._note("%s._acquire_restore()", self)


Looking at the code, this issue exists in python 3.8 as well.

Have you reproduced the issue on 3.8?

I am unable to reproduce this on main (on a Mac). Adding Antoine since I think he fixed a few issues in this area.

RLock is implemented in C nowadays so this problem doesn't occur anymore:
https://github.com/python/cpython/blob/main/Modules/_threadmodule.c#L436-L459

You can of course, however, import the pure Python RLock under the name "_PyRLock", which is still vulnerable to this issue:
https://github.com/python/cpython/blob/main/Lib/threading.py#L204-L206