IGNORE_OSVERSION=yes -- can't install pkg

I just setup a jail from a 12-CURRENT I built awhile ago. It has no ports tree. So I'm attempting
to install svnlite. issuing pkg search svnlite returns
The package management tool is not yet installed on your system.
Do you want to fetch and install it now? [y/N]: y
Bootstrapping pkg from pkg+http://pkg.FreeBSD.org/FreeBSD:12:amd64/latest, please wait...
Verifying signature with trusted certificate pkg.freebsd.org.2013102301... done
[12current.localhost] Installing pkg-1.10.5...
Newer FreeBSD version for package pkg:
To ignore this error set IGNORE_OSVERSION=yes
- package: 1200062
- running kernel: 1200054
Allow missmatch now?[Y/n]:

Umm, what? Should I ignore this error? If so, why is there an error at all?
I answered no. Guess I won't be able to use pkg(8) on this jail(8). :-(

--Chris