Dragging items in a Row layout quickly leaves it in tatters

This was seen with QML viewer compiled from qt/qt-qml source with the HEAD
at 672e06aef096d3e7a81826b28121f3314948eeff

In the tesla demo, after unlocking the "lock screen" there are some icons at the
bottom of the screen. Quickly dragging the rightmost icon all the way to the left
often leave the icons in-between out of alignment with the row layout (after the
initial icon has been dropped in place, slowly dragging an icon across make all
the icons pop back into place). Dragging from left to right it's much harder to trigger
the same problem, but it can be done.