Installation of linux_base-f10.tbz fails: sysctl: unknown oid 'compat.linux.osrelease'

[Yuri]

Reporting an error that I got while installing it from binary:
# pkg_add -r linux_base-f10
Fetching 
ftp://ftp.freebsd.org/pub/FreeBSD/ports/amd64/packages-9.1-release/Latest/linux_base-f10.tbz... 
Done.
sysctl: unknown oid 'compat.linux.osrelease'
linuxulator is not (kld)loaded, exiting
pkg_add: install script returned error status


Yuri