Animated cursors not working on QtWayland

Animated cursors are not working in Qt applications on --platform wayland.

For example the following qml file should use the animated wait cursor when hovering the text:

import QtQuick 2.1;
import QtQuick.Layouts 1.1;

Item {
    width: 200
    height: 200

    GridLayout {
        anchors.fill: parent
        Text {
            text: "Wait"
            MouseArea {
                anchors.fill: parent
                cursorShape: Qt.WaitCursor
            }
        }
    }
}

On platform xcb the cursor is animated, on wayland it's just a static version. I tested with weston (1.8) and KWin (Plasma 5.5 dev branch). Running the test as an X11 application through XWayland in KWin results in an animated cursor.

Grepping through the code shows that neither wl_cursor_frame nor wl_cursor_frame_and_duration are used.