Comment # 16 on bug 980521 from Dr. Werner Fink

(In reply to Martin Szulecki from comment #14)

> There is also an example in the man page of dbus-launch regarding testing for 
> the dbus-daemon but I am not sure if this is the "correct" way:
> https://dbus.freedesktop.org/doc/dbus-launch.1.html

Yep, that is correct ... in sys.xsession this is extend to use dbus-launch
with the option --exit-with-session to let dbus-daemon become one of the parent
processes of the final X session leader (session of window manager).  This is
done the `set' which prefix the final command line with the dbus-launch command
and its options.