Flickable ignores margins when determining the flick direction

When a flickable has the "flickableDirection" property set to Flickable.AutoFlickDirection (the default), if the flickable height is equal to the contentHeight, it will never scroll vertically.

This works fine when topMargin or bottomMargin are set to 0, but fails otherwise. Please try the attached test case: the green rectangle is partially off the viewport, yet it cannot be scrolled up.
If you modify the test case and add "flickableDirection: Flickable.VerticalFlick", then it will start working.

At a first glance, the problem seems to be in QQuickFlickable::[xy]flick(), that don't take the margins into account.