> Wouldn't surprise me, but it seems to work for me.  If anyone has a
> more detailed explanation of what is wrong where, I'll take a look at
> it.

we're now writing the nwa to disk.  this calculation appears to be incorrect.
here's the check in cdfs:

        /* reconcile differing nwas */
        if (aux->mmcnwa != nwa) {
                fprint(2, "%s: nwa from drive %,ld != computed nwa %,ld\n",
                        argv0, aux->mmcnwa, nwa);
                fprint(2, "\tbe careful!  assuming computed nwa\n");
                /* the invisible track may still start at the old nwa. */
                // aux->mmcnwa = nwa;

        }