Changing orientation mode doesn't work correctly

Steps to reproduce:

1. Create an instance of QMainWindow and show it in full screen.
2. mainWindow.setAttribute(Qt::WA_Maemo5AutoOrientation);
3. Rotate the device to portrait mode.
4. mainWindow.setAttribute(Qt::WA_Maemo5PortraitOrientation);
5. Do not rotate the device, keep it still. Then call mainWindow.setAttribute(Qt::WA_Maemo5AutoOrientation)

This causes the application to receive (on N900) a landscape orientation change even (800x480) and then instantly another one for portrait (480x800) even though the application did not change orientation at all between changing the orientation to portrait and then back to automatic. This defect is not reproducible in landscape orientation, just portrait. The actual end-result of this is very nasty flicker in the application due to the erroneous sending of that one extra resize event.