Assert in qqmlengine_p.h when running the following testcase

This testcase works fine in 5.0.2 but crashes/asserts in 5.2.1 and current 5.3.0.

What is happening is that basically the delegate is being released from the list while a function on that very same delegate is being executed. This causes things to go badly.

In main.qml there is a bigger explanation of what i think is going on.