Updates on progress: Cygwin now has a Python 3.12 test package, with corresponding NumPy 2.2 test package.

The Python threading tests (python -m test.test_threading) fail somewhere in tear-down, in situations where they should be calling either a thread-exit function or a process-exit function. My guess is that it's somehow skipping both, leading to a return from pthread_exit, which very shortly leads to a segfault when it runs out of stack. I have not managed to reproduce this in C, and will likely step through pthread_exit with gdb when I have a bit of time to see how it returns.

DWesl#68 tries to run the NumPy tests anyway, and fails (usually in tests that check threading).