This issue should have a much higher priority as it basically breaks Python embedding unless the user either does not re-initialize the interpreter or avoid the use of _datetime.strptime.

We're currently testing with a patch based on Christian and Alexander's idea but using m_free as using m_clear and Py_CLEAR neither makes sense to me nor did it work in conjunction with Py_Finalize when testing it. A version matching the current tip is attached. We did not run into any issues so far (and the only thing I can think of is clearing the static variable too often and thus causing some extra imports).