childrenRect does not take children's transforms into account

Rectangle {
    width: 640; 
    height: 480;
    color: "blue"
    Component.onCompleted: {
        print("Height of children: " + childrenRect.height);
    }

    Rectangle {
        anchors.fill: parent
        scale: 0.5
        rotation: 90
        color: "red"
    }
}