RotationAnimator does not pick up geometry changes correctly

import QtQuick 2.2

Rectangle {
    width: 200
    height: 200

    gradient: Gradient {
        GradientStop { position: 0; color: "palegreen" }
        GradientStop { position: 1; color: "black" }
    }

    Rectangle {
        color: "white"
        width: 5
        height: parent.height / 2
        antialiasing: true
        anchors.centerIn: parent
        RotationAnimator on rotation { from: 0; to: 360; duration: 10000; loops: Animation.Infinite }
    }
}