Animation leaves drawing artifacts when clipping is used

In QML, if an Item has clipping enabled and its scale or position is animated, its children leave a trail of drawing artifacts. See the attached example: when the red Rectangle is clicked, its scale changes, and the scaling is animated.

This does not happen if "clip: true" is removed.

Note this also does not happen if the viewport update mode is set to QGraphicsView::FullViewportUpdate rather than QGraphicsView::BoundingRectViewportUpdate in src/declarative/util/qdeclarativeview.cpp so it seems the region that is being repainted is not correct.