Just got bit by this one. Couldn't unmount an lufs-sshfs
mount because updatedb was running around in there
(Device is busy error, could this be a reason other people
are seeing this message ?)
I don't know about other systems, but on Debian you can
add 'lufs' to the PRUNEFS variable in /etc/updatedb.conf.
Anyway, I think at least a prominent mention in the
README is warranted.
Thanks so much.