Positioner "padding" properties are not accessible in attached case

The revisioned properties of the Positioner (QQuickBasePositioner) like padding, topPadding, leftPadding, rightPadding, bottomPadding are not available if the positioner is accessed through a attached property:

import QtQuick 2.6
import QtQuick.Window 2.2

Window {
    visible: true
    Row {
        spacing: 1 // ok
        padding: 10 // ok

        anchors.fill:parent
        Rectangle {
            Positioner.spacing: 1 // ok
            Positioner.padding: 10 // Cannot assign to non-existent property "padding"
        }
    }
}

This is caused by QTBUG-40043 . Usually this is worked around by not revisioning at all for objects representing attached properties, but Positioner can be also used directly through one of its subtypes (Row, Column ...).