Wrong child size when resizing a ColumnLayout with both anchors and "height" set

ApplicationWindow {
    visible: true
    width: 640
    height: 480

    ColumnLayout
    {
        id: layout
        anchors.fill: parent
        anchors.margins: spacing
        height: parent.height/3
        Rectangle
        {
            Layout.fillHeight: true
            Layout.fillWidth: true
        }
        Rectangle
        {
            Layout.fillHeight: true
            Layout.fillWidth: true
        }
    }

    Rectangle
    {
        anchors.fill: layout
        color: "transparent"
        border.color: "red"
    }
}