QML Shape asynchronous z-ordering issue

When Shape contains other QML elements after (asynchronous) ShapePath, it doesn't respect QML z ordering. See attached images.

Steps to reproduce:
1) Clone QNanoPainter from https://github.com/QUItCoding/qnanopainter
2) Enable "asynchronous: true" in qnanopainter_vs_qpainter/qml/shapeitem/FlowerComponent.qml
3) Run the demo.
4) From top-right corner settings, enable only "Render flower" test and adjust "Rendering count" to 2.
5) Switch to "QML Shape" rendering.

Expected:
Flower is rendered with white circle on center.

Actual:
Flower is rendered with white circle behind it.

It seems that enabling asynchronous rendering messes up Shape z ordering so that content from ShapePath gets rendered over Rectangle which becomes after that in QML.