Preupgrade Q? unsure if bug.

[Frank Murphy]

Have and f8 box, that also runs rawhide from an external usb-h\d (always
in\on)

Ran preugrade on f8.
After rebooting, gave me the choice of upgrading f8 or rawhide
Choose f8.

Wouldn't continue as is said both filesystems were identified(labelled)
as f8.

Both were initially installed from f8-live 

with the rawhide going f8-live>f9Beta>rawhide

Aside from disconnecting the usb, not an easy task here.
What can be done.

Frank