lock violation in unionfs (9.0-STABLE r230270)

[Pavel Polyakov]

http://www.freebsd.org/cgi/query-pr.cgi?pr=165087

Occurs simply trying to use unionfs:
mount -t unionfs -o noatime /usr /mnt

insmntque: mp-safe fs and non-locked vp: 0xfffffe01d96704f0 is not  
exclusive locked but should be
KDB: enter: lock violation

Its possible to continue tho.
Then locks encounter on every file/dir access under mounted path.
It can be resumed from KDB, but sometimes leads to deadlock and system  
freezes at "db> " prompt.