Trying to install 6.0 from hard disk, with the dist sitting
on a filesystem which is regularly mounted as /u2 in my
fstab, the install failed while trying to mount all the
filesystems listed in my fstab.  The error was (approx):
"device is already mounted -- using symlink", followed by
"file or directory exists".  It then unmounted everything
and
gave up.

It presented a re-try button which incidentally did nothing
worthwhile at all, since it didn't even try to re-mount the
filesystems that had been unmounted after the error, but
that should be a separate bug if at all.

I worked around this fairly easily by removing the
filesystem containing the 6.0 dist from my fstab and
restarting the install.