QCameraViewfinder broken scaling with QT::KeepAspectRatio on Windows 10

Steps to reproduce (hint: the example in multimediawidgets/camera resembles these steps):

• use Qt 5.6.0 on Windows 10 with a webcam
• take a QCameraViewfinder widget
• setAspectRatioMode(Qt::KeepAspectRatio);
• resize it so that the widget's width gets smaller than the camera's native image but the hight bigger than the camera's natives image

Result: The camera's image gets painted once in a whole, squeezed horizontally, starting at the top-left of the widget. The following frames are updated in a correct scaled rectangle, correctly centered vertically in the widget. But the content of that updated rectangle is only the part of the squeezed image, overlapping the correctly scaled rectangle. The part of the image, not overlapping the correct rectangle remains freezed until the next resizeEvent.