Possible Bug in tbytevector

[Rich Collins]

I ran into a bug copying the tags from an mp3 to an ogg when the  
comment tag was empty.

void ByteVector::setData(const char *data, uint length)
{
   detach();

   resize(length);
   ::memcpy(DATA(d), data, length);
}

data was an empty string and length was 0.

DATA(d) is expanded to &(d->data[0]), but d->data is empty