Bug#942140: Unable to reboot/shut down from GDM

[Алексей Шилин]

Package: gnome-session
Version: 3.34.1-1

After upgrading gnome-session packages from version 3.30 to 3.34, I'm
unable to shut down the system from the top-right menu in GDM anymore:
the confirmation dialog does appear, but clicking on either Reboot or
Power Off has no effect.

syslog contains the following related messages:

Oct 10 20:17:19 debian gnome-session[639]: gnome-session-binary[639]:
WARNING: Shutdown failed:
GDBus.Error:org.freedesktop.DBus.Error.InteractiveAuthorizationRequired
: Interactive authentication required.
Oct 10 20:17:19 debian gnome-session-binary[639]: WARNING: Shutdown
failed:
GDBus.Error:org.freedesktop.DBus.Error.InteractiveAuthorizationRequired
: Interactive authentication required.
Oct 10 20:17:19 debian gnome-session-binary[639]: Entering running
state
Oct 10 20:17:19 debian gnome-shell[646]: Ignored exception from dbus
method: Gio.IOErrorEnum:
GDBus.Error:org.gtk.GDBus.UnmappedGError.Quark._g_2dio_2derror_2dquark.
Code19: Действие было отменено

Interestingly enough, shutting down from a user session works fine.

(I'm reporting against gnome-session and not gdm3 because upgrading the
latter from 3.30 to 3.34 doesn't lead to this bug; it's gnome-session
packages which, when upgraded, make this issue appear.)