Canvas context putImageData bug

import QtQuick 2.0
import QtQuick.Window 2.0

Window {
    visible: true
    width: 300
    height: 300

    Canvas {
        anchors.fill: parent

        onPaint: {
            var ctx = getContext("2d")
            ctx.fillStyle = "red"
            ctx.fillRect(10, 10, 50, 50)
            var copy = ctx.getImageData(10, 10, 50, 50)
            ctx.putImageData(copy, 70, 70)
        }
    }
}