Using ext4 usb drive to go to 13.1.0

[Bruno Wolff III]

When I upgraded my XO 1.75 to 12.1.0 I was able to use my ext4 formatted 
USB drive without an issue. The instructions for going to 13.1.0 are different 
and when at the openfirmware command line it doesn't appear that my USB 
drive's file system is detected. I didn't see any commands listed to see 
what drives were mounted (in the event it wasn't mounted as u:).

This is a bit of a regression from the previous version.

I haven't tried the online update as I didn't want to redownload the update 
file again.

I see there is a zsp file for 13.1.0, but I wasn't sure I could just rename 
it to fs2.zip and have things work like they did for the 12.1.0 install.