[REG 5.4->5.5] QString::simplified() fails to replace newlines by ' ' if length is unchanged

#include <QString>
#include <QDebug>

int main(int argc, char *argv[])
{
    QString s = QLatin1String(QT_VERSION_STR) + QLatin1String("\nbla\nbla");
    qDebug() << s << "simplified:" << s.simplified();
    return 0;
}

"5.4.2
bla
bla" simplified: "5.4.2 bla bla"

"5.5.0\nbla\nbla" simplified: "5.5.0\nbla\nbla"

if (newlen == str.size()) {
            // nothing happened, return the original