QMimeDatabase: File with "diff" followed by tab character is not recognized as text/x-diff

#include <QBuffer>
#include <QMimeDatabase>
#include <QDebug>

int main(int argc, char *argv[])
{
    static const char data[] = "diff\t";
    QByteArray d(data);
    QBuffer buff(&d);
    QMimeDatabase mdb;
    qDebug() << mdb.mimeTypeForFileNameAndData(QLatin1String("blah"), &buff).name();

    return 0;
}