Whether this is a real bug or not, I don't know. My disks weren't unmounted cleanly before
I tried upgrading from RedHat 7 to Fisher. The installer didn't like that and segfaulted. I'd
copy in the debugging output that was there but I don't have a floppy drive and wasn't
going to write down 50 lines of python debugger output. :) Rebooting and letting a fsck do
its job fixed the problem.
Fixed thanks for the report.