bug#25136: locale confusion

[Dave Love]

I followed the instructions for getting locales working in
"(guix)Application Setup" to no effect initially.  I'm running over
RHEL6, if that's relevant, and I have:

  $ locale
  LANG=en_GB.UTF-8
  LC_CTYPE="en_GB.UTF-8"
  LC_NUMERIC="en_GB.UTF-8"
  LC_TIME="en_GB.UTF-8"
  LC_COLLATE="en_GB.UTF-8"
  LC_MONETARY="en_GB.UTF-8"
  LC_MESSAGES="en_GB.UTF-8"
  LC_PAPER="en_GB.UTF-8"
  LC_NAME="en_GB.UTF-8"
  LC_ADDRESS="en_GB.UTF-8"
  LC_TELEPHONE="en_GB.UTF-8"
  LC_MEASUREMENT="en_GB.UTF-8"
  LC_IDENTIFICATION="en_GB.UTF-8"
  LC_ALL=
  $ export -p | grep GUIX
  declare -x GUIX_LOCPATH="/home/dlove/.guix-profile/lib/locale"
  $ find $GUIX_LOCPATH -name en_GB.UTF-8
  /home/dlove/.guix-profile/lib/locale/2.24/en_GB.UTF-8

but saw this (note the warning):

  $ guix --version 
  warning: failed to install locale: Invalid argument
  guix (GNU Guix) 20161208.12
  Copyright (C) 2016 the Guix authors
  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
  This is free software: you are free to change and redistribute it.
  There is NO WARRANTY, to the extent permitted by law.

strace showed it looking in "locale/2.23", not "locale/2.24", despite
the environment.

"guix" there was from the /usr/local/bin link suggested by the
installation instructions.  After a "guix package -i guix" (to the same
version of guix, but now in .guix-profile), I don't get the warning but
I wonder why that should have made a difference and why the environment
seems to be ignored.