QPainterPath::subtracted() sometimes ends up with an incorrect path

QPainterPath::subtracted() sometimes ends up with an incorrect path. In the attached case there are two pies created and after subtracting one from the other it should only show the outer part of the main pie, but depending on the angle it might end up showing the whole thing.

In the attached example, the initial angle is fine, but if you move the slider you can see where it is having some problems.