QMultiHash::operator==() returns false for two empty hashes

//Qt
#include <QtCore/QCoreApplication>
#include <QtCore/QVariantMap>
#include <QtCore/QString>
#include <QtCore/QTimer>
#include <QtCore/QObject>
#include <QMultiHash>

int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);
    QMultiHash<QString,QString> a, b;

    qWarning() << "A == B ? " << (a == b); // expect true, actual true

    a.insert(QStringLiteral("1"), QStringLiteral("1.a"));
    a.insert(QStringLiteral("1"), QStringLiteral("1.b"));

    qWarning() << "A == B ? " << (a == b); // expect false, actual false

    a.remove(QStringLiteral("1"));

    qWarning() << "A.isEmpty() -> " << a.isEmpty(); // expect true, actual true
    qWarning() << "B.isEmpty() -> " << b.isEmpty(); // expect true, actual true

    qWarning() << "A -> " << a; // QMultiHash()
    qWarning() << "B -> " << b; // QMultiHash()

    qWarning() << "A == B ? " << (a == b); // expect true, actual false

    return 0;
}