[gnome-shell/gnome-3-34] data: Enable clean session shutdown after gnome-shell failure

[Florian Müllner <fmuellner src gnome org>]

commit af958838072dae72cbbeea00b3246e08739e7da0
Author: Benjamin Berg <bberg redhat com>
Date:   Mon Nov 25 15:15:01 2019 +0100

    data: Enable clean session shutdown after gnome-shell failure
    
    If the GNOME shell crashes, we run a service that may disable
    extensions. This is important so that users will not be locked out of
    their own session in case an extension is causing crashes.
    
    As this is a very agressive action, we tried to only do this in the
    first two minutes of the session. Unfortunately, the logic was broken
    and would result in an unclean session shutdown.
    
    Fix this by using the newly introduced gnome-shell-disable-extensions
    file. This is created by the extension subsystem for a period of time to
    indicate the extensions may be the cause of a gnome-shell failure.
    
    See
      https://gitlab.gnome.org/GNOME/gnome-session/issues/43
    for a log of the bug happening and the gnome-session part to fix this.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/858

 data/gnome-shell-disable-extensions.service | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
---
diff --git a/data/gnome-shell-disable-extensions.service b/data/gnome-shell-disable-extensions.service
index d55d7ed879..de91167c58 100644
--- a/data/gnome-shell-disable-extensions.service
+++ b/data/gnome-shell-disable-extensions.service
@@ -1,11 +1,12 @@
 [Unit]
 Description=Disable GNOME Shell extensions after failure
+# Note that this unit must not conflict with anything, and must
+# be able to run in parallel with the gnome-session-shutdown.target.
 DefaultDependencies=no
 
-# Only disable extensions for a short period of time after login.
-# This means we err on the side of failing the first login after a broken
-# extension was installed.
-Requisite=gnome-session-stable.timer
+# We want to disable extensions only if gnome-shell has flagged the extensions
+# to be a likely cause of trouble.
+ConditionPathExists=%t/gnome-shell-disable-extensions
 
 [Service]
 Type=simple