freebsd-update not working from 7.1-PRERELEASE

[Colin Percival]

Markus Oestreicher wrote:
> I installed 7.1-BETA-i386 from CD and used freebsd-update to get the latest
> prerelease updates.
> 
> This got me to the following version:
> 
> $ uname -a
> FreeBSD hostname 7.1-PRERELEASE-p1 FreeBSD 7.1-PRERELEASE-p1 #0: Sun Oct  5 12:15:12 UTC 2008     root at i386-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC  i386

Hmm.  I wonder why that's -PRERELEASE- instead of -BETA-.  There might be a bug
in the FreeBSD Update build code here...

> Fetching metadata signature for 7.1-PRERELEASE from update1.FreeBSD.org... failed.

Right, FreeBSD Update thinks you're running 7.1-PRERELEASE (i.e., "somewhere 
recent on the 7-STABLE branch, but we don't know exactly where") instead of 
7.1-BETA (which is a very specific point on the branch -- specific enough that
FreeBSD Update can figure out what your system should have installed and how
to update it).

The best solution here is to make FreeBSD Update realize that you're running
7.1-BETA:
# env UNAME_r=7.1-BETA freebsd-update [...]

Colin Percival