QGraphicsSceneFindItemBspTreeVisitor crashes

Steps to reproduce / test case:

• Create QWidget with a QGraphicsView and Scene
• Add small boxes (custom QGraphicsItem widget) (I do about 800 at a time) until I have approximately 20k items
• Catch a key press event in the parent QWidget which calls a delete routine that removes approximately 800 graphicsitems at once.
• Hold down key so it runs VERY quickly and possibly get the crash:

More information:

if (!item->d_func()->itemDiscovered && item->isVisible()) {

in the titles function is where it crashes.