QGraphicsItem: setZvalue() to a previously unassigned number causes QGraphicsScene to crash when closing the application

If, for example, three QGraphicsItems are added to a scene and their z-value is set explicitly to 1, 2 and 3 respectively and I then move one of the existing QGraphicsItems to z-value 0, the scene crashes in its destructor when closing the application.
To reproduce, use the following sample code:

//#include <QtGui>
//
//static QGraphicsScene *myScene;
//static QList<QGraphicsRectItem *> *myList;
//
//class GraphicsView: public QGraphicsView
//{
// Q_OBJECT
//
//public:
// GraphicsView(QGraphicsScene *scene, QWidget *parent):
// QGraphicsView(scene,parent) {}
//
//public slots:
// void moveToBackground();
//};
//
//void GraphicsView::moveToBackground()
//

{ // QGraphicsItem *item=myList->at(2); // //myScene->removeItem(item); // item->setZValue(0); // //myScene->addItem(item); //}

//
//#include "main.moc"
//
//int main(int argc, char **argv)
//{
// QApplication app(argc, argv);
//
//
// myScene= new QGraphicsScene;
// myScene->setSceneRect(0, 0, 800, 480);
// myScene->setItemIndexMethod(QGraphicsScene::NoIndex);
//
// QList<QGraphicsRectItem *> list;
// myList=&list;
// list.append(new QGraphicsRectItem(10,15,20,25));
// list.append(new QGraphicsRectItem(20,17,20,25));
// list.append(new QGraphicsRectItem(14,24,20,25));
//
// QColor colors[3]=

{ // QColor(Qt::red), //z==1 // QColor(Qt::green), //z==2 // QColor(Qt::blue) //z==3 // }

;
//
// for (int i=0; i < 3; ++i)

{ // list[i]->setFlag(QGraphicsItem::ItemIsMovable); // list[i]->setFlag(QGraphicsItem::ItemIsSelectable); // list[i]->setZValue(i+1); // list[i]->setPen(QPen(colors[i])); // myScene->addItem(list[i]); // }

// myScene->setBackgroundBrush(Qt::white);
// GraphicsView *view = new GraphicsView(myScene,NULL);
// QAction *pAct=new QAction(view);
// new QShortcut(QString::fromLatin1("A"),view,SLOT(moveToBackground()),SLOT(moveToBackground()));
// QObject::connect(pAct,SIGNAL(triggered()),view,SLOT(moveToBackground()));
//
// view->show();
// return app.exec();
// myScene->clear();
// return 0;
//}

#include <QtGui>

static QGraphicsScene *myScene;
static QList<QGraphicsRectItem *> *myList;

class GraphicsView: public QGraphicsView
{
Q_OBJECT

public:
GraphicsView(QGraphicsScene *scene, QWidget *parent):
QGraphicsView(scene,parent) {}

public slots:
void moveToBackground();
void sceneDestroyed();
};

void GraphicsView::moveToBackground()
{
QGraphicsItem *item=myList->at(2);
//myScene->removeItem(item);
item->setZValue(0);
//myScene->addItem(item);

}
void GraphicsView::sceneDestroyed()
{
qDebug() << "scene destroyed";
}
#include "main.moc"

int main(int argc, char **argv)
{
QApplication app(argc, argv);

QGraphicsScene scene;
myScene=&scene;
scene.setSceneRect(0, 0, 800, 480);
scene.setItemIndexMethod(QGraphicsScene::NoIndex);

QList<QGraphicsRectItem *> list;
myList=&list;
list.append(new QGraphicsRectItem(10,15,20,25));
list.append(new QGraphicsRectItem(20,17,20,25));
list.append(new QGraphicsRectItem(14,24,20,25));

QColor colors[3]=

{ QColor(Qt::red), //z==1 QColor(Qt::green), //z==2 QColor(Qt::blue) //z==3 }

;

for (int i=0; i < 3; ++i)

{ list[i]->setFlag(QGraphicsItem::ItemIsMovable); list[i]->setFlag(QGraphicsItem::ItemIsSelectable); list[i]->setZValue(i+1); list[i]->setPen(QPen(colors[i])); scene.addItem(list[i]); qDebug() << list[i]->zValue(); }

scene.setBackgroundBrush(Qt::white);
GraphicsView *view = new GraphicsView(&scene,NULL);
QAction *pAct=new QAction(view);
new QShortcut(QString::fromLatin1("A"),view,SLOT(moveToBackground()),SLOT(moveToBackground()));
QObject::connect(pAct,SIGNAL(triggered()),view,SLOT(moveToBackground()));
QObject::connect(qobject_cast<QObject*>(myScene),SIGNAL(destroyed()),view,SLOT(sceneDestroyed()));
view->show();
return app.exec();
}

Press "a" on the keyboard to trigger the slot which changes the z-order of the last item in the list. Then close the application. A crash is seen which originates in the destructor of QGraphicsScene.