Problem with QJSEngine, variables get "random" values during script execution

We use some eval.js scripts to create automated tests.

Up to 5.1.x, the attached script did work and the

var assertion_line_1 = -1, assertion_line_2 = -1;

variables got filled with the correct values 6 and 7 during script execution.

With Qt 5.2.0, it seems that the loop still does the right thing but afterwards, the content of assertion_line_1 is random garbage :/

The interfaces used in that script are all plain dumb auto-wrapped via newQObject and use only simple types like QString and so on.