Assertion error in new scenegraph renderer.

When I test my QtQuick application (relatively complex) on 5.2 Beta1, I get the following assertion error quite often but randomly.

-/
ASSERT: "m_nodes.contains(node)" in file scenegraph\coreapi\qsgbatchrenderer.cpp, line 1170
/-

Stacktrace attached as a file.

UPDATE:
I managed to narrow down the causing situation. It doesn't assert in simpler QML file but the attached CrashTest.zip example project shows weird behaviour that I'm sure is related to the assert. When items are placed into Column, and each item has animations, the animation is applied to all the items in that column - for some reason. Just hover over the first items in the column and observe the opacity change.