QObject::diconnectNotify is not called when receiver is destroyed

#include <QObject>

class DisconnectTest: public QObject
{
    Q_OBJECT

        signals:
        void testSignal();

protected:
    void connectNotify(char const * signal)
    {
        std::cout << "signal \"" << signal << "\" connected" << std::endl;
    }

    void disconnectNotify(char const * signal)
    {
        std::cout << "signal \"" << signal << "\" disconnected" << std::endl;
    }
};

int main()
{
    QObject * dummy = new QObject;
    DisconnectTest * test = new DisconnectTest;

    // the slot does not matter here, we never emit the signal anyway
    QObject::connect(test, SIGNAL(testSignal()), dummy, SLOT(deleteLater()));

    // here the disconnectNotify() should be called (the receiver is destroyed and the slot is disconnected), but it does not
    delete dummy;

    // cleanup
    delete test;

    return 0;
}