On GuixSD as of v0.9.0-1430-g234ea8a, attempts to talk to upowerd over D-Bus fail:
--8<---------------cut here---------------start------------->8--- $ sudo dbus-send --print-reply --system --dest=org.freedesktop.UPower /org/freedesktop/UPower org.freedesktop.UPower.Suspend Error org.freedesktop.DBus.Error.UnknownMethod: Method "Suspend" with signature "" on interface "org.freedesktop.UPower" doesn't exist --8<---------------cut here---------------end--------------->8--- See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg01004.html>. Ludo’.
