macOS native dialogs don't support setting directory

[altendky]

Need to report this to Qt. Non-native dialog works.

1197:preqtrio administrator$ venv/bin/python x.py
/Users/administrator/preqtrio/blue

import os
import pathlib

from PyQt5 import QtWidgets

p = (pathlib.Path('blue') / 'red').resolve()
parent = p.parent
parent.mkdir(parents=True, exist_ok=True)

app = QtWidgets.QApplication([])
if not parent.is_dir():
    raise Exception('parent is not a directory')
s = os.fspath(parent)
print(s)
dialog = QtWidgets.QFileDialog(directory=s)
dialog.selectFile(os.fspath(p))
dialog.show()
app.exec_()