Campbell Barton
5edba9b42f
Calling PyEval_ReleaseLock() was crashing with Python 3.9 because it accessed the NULL pointer set by PyThreadState_Swap(). This happened when calling ViewLayer.update() for example. While the existing logic could be fixed by swapping the thread-state back before calling PyEval_ReleaseLock(), this depends on functions which are tagged to be removed by v4.0. Replace use of deprecated functions by calling PyEval_SaveThread(), instead of inlining the logic, using _PyThreadState_UncheckedGet() to prevent Python aborting. The call to PyEval_ThreadsInitialized has been removed as threads are now initialized with Python. This could be replaced with Py_IsInitialized() however it doesn't look like this is necessary. This is compatible with Python 3.7 & 3.9.