Regression: UTF-32 codec fails on assert when fromUnicode() is called

#include <QDebug>
#include <QFile>
#include <QTextCodec>

int main(int argc, char *argv[])
{
    QTextCodec *codec = QTextCodec::codecForName("UTF-32");
    if (!codec) {
        qDebug() << "Could not find codec for UTF-32";
        return 0;
    }
    QFile file("dialog.ui");
    if (!file.open(QIODevice::ReadOnly)) {
        qDebug() << "Can't open input file.";
        return 0;
    }
    const QByteArray data = file.readAll();
    file.close();

    qDebug() << "About to transform";
    const QString str = codec->toUnicode(data);
    const QByteArray newData = codec->fromUnicode(str);
    qDebug() << "All went fine";
    return 0;
}

ASSERT: "end - ba.constData() == length" in file /home/jarek/dev/qt-62/qtbase/src/corelib/text/qstringconverter.cpp, line 1030