Tested again on Windows and it still works :). I suggest to merge.
N.B. The `py` launcher on Windows is a bit strange: it seems to try to auto-detect the desired Python version and it fails (at least sometimes). A simple Hello-World program using Python3 syntax can be compiled with `py -m py_compile` as the launcher chooses Python3 but executing it with `py "%f"` chooses Python2, for whatever reason. But since this happens also in the terminal, it is unrelated to this PR and Geany in general.