QImageReader::supportedSubTypes returns invalid result

QList<QByteArray> QImageReader::supportedSubTypes() const
{
 if (!d->initHandler())
  return QList<QByteArray>();
 if (!d->handler->supportsOption(QImageIOHandler::SupportedSubTypes))
  return d->handler->option(QImageIOHandler::SupportedSubTypes).value<    QList<QByteArray> >();
 return QList<QByteArray>();
}