ListView positionViewAtIndex ignores ListView.End

Reproduce:

    ListView {
        model: 1000
        anchors.fill: parent
        delegate: Text

        Component.onCompleted: positionViewAtIndex(500, ListView.End)
    }

Expected behavior: The ListView should align the 500th item with the bottom of the view.
Observed behavior: The ListView aligns the 500th item with the top of the view.