kern/122833: mountd fails on nmount() after UFS snapshot creation with mount

[Leon Kos]

To prove that this is not worksforme kind of bug, I've installed vanilla
FreeBSD 7.0 from distribution CD. Created /etc/exports with single line
/usr -network 127.0
After command "mount -u -o snapshot /usr/.snap/daily.0 /usr"
I'am getting  messages of Cross-device link and bad exports line.

Forgot to mention before, but this does not happen on 6.3-STABLE. I've been 
running NFS for years and snapshoting daily without a problem on 6_RELENG