Test case.

output-qt-4.8.0.txt

$ qnam.app/Contents/MacOS/qnam 
Sending request 
Value:  QVariant(int, 1337) 

output-qt-5.0.0.txt

$ qnam.app/Contents/MacOS/qnam
Sending request 
Nope :-( 

$ qmake --version
QMake version 2.01a
Using Qt version 5.0.0 in /Users/ahf/src/nokia/qt5/qtbase/lib

test.cpp

#include <QAuthenticator>
#include <QCoreApplication>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QObject>
#include <QUrl>
#include <QVariant>
#include <QtDebug>

class TestCase : public QObject {
    Q_OBJECT

public:
    TestCase(QObject *parent = 0) :
        QObject(parent)
    {
        m_manager = new QNetworkAccessManager(this);
        connect(m_manager, SIGNAL(authenticationRequired(QNetworkReply*, QAuthenticator*)), SLOT(authenticationRequired(QNetworkReply*, QAuthenticator*)));

        QObject *originatingObject = new QObject;
        originatingObject->setProperty("test_case_value", QVariant(1337));

        QNetworkRequest request;
        request.setUrl(QUrl("http://koivi.com/php-http-auth/protect.php"));
        request.setOriginatingObject(originatingObject);

        qWarning() << "Sending request";
        m_manager->get(request);
    }

    ~TestCase()
    {
    }

private slots:
    void authenticationRequired(QNetworkReply *reply, QAuthenticator *authenticator)
    {
        Q_UNUSED(authenticator);

        QObject *originatingObject = reply->request().originatingObject();

        if (originatingObject)
            qWarning() << "Value: " << originatingObject->property("test_case_value");
        else
            qWarning() << "Nope :-(";
    }

private:
    QNetworkAccessManager *m_manager;
};

int main(int argc, char *argv[])
{
    QCoreApplication application(argc, argv);
    TestCase test;

    return application.exec();
}

#include "test.moc"