iocage specific 12.0-RELEASE -> STABLE/12

[Russell L. Carter]

Greetings,

While I wait on poudriere to build both firefox and chromium (32
threads, and it will still take a while), so that I can install iocage
and dive into this newfangled technology called "jails" ;-), I have a
basic question.

I had a flash in the brain (be nice, I'm a geezer and slow, it's only
taken me 20 years to figure this out) and realized I might be able to
use iocage jails to quickly spin up dev environments that are skeletal
compared to my desktop environment and so can minimize package version
collisions that happen when I try to port stuff to FreeBSD.  So I want
the FreeBSD version of the jail to match the commit of my stable/12
host, including packages.  However the iocage docs don't seem to
mention this possibility.  Is this something people do?  I am guessing
I can nfs mount my (different) build box's /usr/src, /usr/obj, and my
package export directories into the jail, and use my source upgrade
scripts and pkg upgrade as usual, correct?  Are there any gotchas I
should be aware of?  Will the template mechanism make it easy to do
the configuration just once, or is iocage expecting a point RELEASE,
as suggested by the docs?

I got to this point pondering how to install gnutls with guile
bindings, so that I can see if I can get guix working on stable/12.

Thanks,
Russell