bug#22981: guix-edit does not find git checkout directory

[myglc2]

Situation: GuixSD sysetm managaed by user glc using a git checkout in
/home/glc/sre/guix.

Problem: When I follow the manual to set up a vanila user (glc5) with a
separate git checkout in /home/glc5/src/guix, guix-edit does not find
the checkout source.

Note: I followed comments from the #guix irc channel to set links in glc
and root that point to the glc checkout:

address@hidden ~/src/guix [env]$ stat ~/.config/guix/latest
  File: ‘/home/glc/.config/guix/latest’ -> ‘../../src/guix’

address@hidden ~/src/guix [env]$ stat /root/.config/guix/latest
  File: ‘/root/.config/guix/latest’ -> ‘/home/glc/src/guix’


CREATE USER glc5
================

address@hidden ~/src/guix$ guix environment guix
address@hidden ~/src/guix [env]$ ./bootstrap
address@hidden ~/src/guix [env]$ ./configure --localstatedir=/var && make

address@hidden ~/src/guix [env]$ git branch -v
* master ff22f01 gnu: dropbear: Update to 2016.72 [fixes CVE-2016-3116].

address@hidden ~/src/guix [env]$ which guix
/run/current-system/profile/bin/guix

address@hidden ~/src/guix [env]$ stat /run/current-system/profile/bin/guix
  File: ‘/run/current-system/profile/bin/guix’ ->
  ‘/gnu/store/3lg5c1nidbj0kjdz5b63hn3vp29kzf0s-guix-0.9.0.c3f29bc/bin/guix’

address@hidden ~/src/guix [env]$ sudo guix system reconfigure 
../configs/c05system.scm

USER glc5 test
==============

address@hidden ~/src$ which guix
/run/current-system/profile/bin/guix

address@hidden ~/src$ stat /run/current-system/profile/bin/guix File:
  ‘/run/current-system/profile/bin/guix’ ->
  ‘/gnu/store/3lg5c1nidbj0kjdz5b63hn3vp29kzf0s-guix-0.9.0.c3f29bc/bin/guix’

address@hidden ~/src$ stat ~/.config/guix/latest
stat: cannot stat ‘/home/glc5/.config/guix/latest’: No such file or directory

## set up glc5's environment
address@hidden ~/src$ guix package -m glc5.scm 

## customize emacs following "8.3 The Perfect Setup"

address@hidden ~/src$ cat ~/.emacs.d/init.el | head -n4
;; from "8.3 The Perfect Setup"
;; Assuming the Guix checkout is in ~/src/guix.
(with-eval-after-load 'geiser-guile
  (add-to-list 'geiser-guile-load-path "~/src/guix"))

## clone guix
address@hidden ~/src$ git clone t://git.savannah.gnu.org/guix.git

### run emacs
emacs

M-x guix-edit screen

Problem: This finds read-only screen.src in store rather than in ~/src/guix/...

c05system.scm
Description: Binary data

glc5.scm
Description: Binary data