QGraphicsGridLayout column spacing affects size even after item removal

void SpacingTest::columnSpacing()
{
    QGraphicsScene scene;
    QGraphicsView view(&scene);
    QGraphicsWidget *widget = new QGraphicsWidget(0, Qt::Window);
    QGraphicsGridLayout *layout = new QGraphicsGridLayout();
    scene.addItem(widget);
    widget->setLayout(layout);
    populateLayout(layout, 2, 1);
    layout->setContentsMargins(0, 0, 0, 0);
    layout->setColumnSpacing(0, 20);
    view.show();
    widget->show();
    layout->removeAt(1);
    layout->removeAt(0);
    widget->resize(widget->effectiveSizeHint(Qt::MinimumSize));
    QApplication::processEvents();

    QCOMPARE(layout->preferredSize(), QSizeF(0, 0)); // is (20,0)

    delete widget;
}