Debug Crash with VS19 and Python 3.9

[thomas kipp]

Itom All in One MSVC2019-Qt5.14.2-x64

If python debugging is enabled in itom, executing code in console or with F9 leads to a crash with the following output in the console:

Itom-Application caught an unknown exception from: (ito::PythonEngine) from event type 43 (MetaCall)

Afterwards the console stays blocked but the execution cannot be interrupted. Itom can not be closed.

When executed with VS-Debugger an exception is thrown in pythonEngine.cpp (line 2068):

else if (PyErr_Occurred() == PyExc_SyntaxError)

Access violation reading location 0x0000000000000058.

[thomas kipp]

It works with python 3.7.2

[thomas kipp]

Python 3.9.4 also fails.

[M. Gronle]

Fixes issue #164: If PyErr_Occurred() is called, the Python GIL must be hold for Python >= 3.9.

→ <<cset 908ab0ea7768>>