bug#37123: gnome-shell: LD_LIBRARY_PATH setting propagates to entire session

[Mark H Weaver]

Since commit 2b0c755d195c79bfc95cdbe802e1e2dea1adb7a2 in August 2018,
our 'gnome-shell' executable has been wrapped by a script that sets
LD_LIBRARY_PATH.

One consequence of this, which I just noticed, is that if 'gnome-shell'
is based on 'core-updates' (or in my case, 'core-updates-next'), many
programs based on 'master' will fail to run within the resulting GNOME
session.

I ran into this issue because I recently rebuilt my Guix system based on
'core-updates-next' and booted into it, although it will take more time
to finish rebuilding my user profile.  Many programs, including Emacs
and Nautilus, fail to launch.  A workaround is to launch a terminal,
unset LD_LIBRARY_PATH within the resulting shell, and then manually run
the other programs from within that shell.  (Since then, I've built a
trimmed-down version of my profile based on 'core-updates-next'.)

I was unable to easily find an existing bug report tracking this issue,
so I created this one.

       Mark