[gnome-shell/wip/clean-the-slate] data: ensure systemd environment is sanitized when shell exits

[Ray Strode <halfline src gnome org>]

commit 3362d74668caebcda9e8e11de1b3b7a83bcae914
Author: Ray Strode <rstrode redhat com>
Date:   Wed Mar 25 16:30:46 2020 -0400

    data: ensure systemd environment is sanitized when shell exits
    
    When mutter is acting as a display server it sets a number of
    environment variables in the user's session. These variables
    tell applications where the display server's sockets are.
    
    When the shell exits at logout time it leaves these environment
    variables in the systemd --user environment, which can confuse
    subsequent sessions.
    
    This commit clears up the environment on exit.

 data/gnome-shell-wayland.service.in | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/data/gnome-shell-wayland.service.in b/data/gnome-shell-wayland.service.in
index 04f94af2d6..100be7f0f1 100644
--- a/data/gnome-shell-wayland.service.in
+++ b/data/gnome-shell-wayland.service.in
@@ -19,6 +19,10 @@ Before=gnome-session-initialized.target
 [Service]
 Type=notify
 ExecStart=@bindir@/gnome-shell
+
+# unset some environment variables that were set by the shell and won't work now that the shell is gone
+ExecStopPost=-systemctl --user unset-environment GNOME_SETUP_DISPLAY WAYLAND_DISPLAY DISPLAY XAUTHORITY
+
 # Exit code 1 means we are probably *not* dealing with an extension failure
 SuccessExitStatus=1
 # On wayland we cannot restart