Well, I went ahead and took five steps back, since nothing seemed to be working, and, for posterity's sake, it turns out that a freshly car2-builder-20011022.upgrade'd music partition looks like this:

empeg:/drive0# ls -liAR

.:

total 14

    129 drwxr-xr-x    2 0        0            1024 Aug 21 15:59 fids

     11 drwxr-xr-x    2 0        0           12288 Aug 21 15:58 lost+found

    257 drwxr-xr-x    2 0        0            1024 Aug 21 15:59 var



./fids:

total 0



./lost+found:

total 0



./var:

total 0