Fixes <https://issues.guix.gnu.org/55444>.
Previously shepherd and dbus-daemon would race to start elogind. In
some cases (for instance if one logs in quickly enough on the tty),
dbus-daemon would "win" and start elogind before shepherd has had a
chance to do it. Consequently, shepherd would fail to start elogind and
mark it as stopped and disabled, in turn preventing services that depend
on it such as 'xorg-server' from starting.
* gnu/services/desktop.scm (elogind-dbus-service): Rewrite to refer to a
wrapper that waits for the 'elogind' Shepherd service.
Ludovic Courtès
f383838a09