units: order user-runtime-dir@.service after systemd-user-sessions.se…

…rvice

We use systemd-user-sessions.service as barrier when to allow login
sessions. With this patch user@.service is ordered after that too, so
that any login related code (which user-runtime-dir@.service is) is
guaranteed to run after the barrier, and never before.

units/user-runtime-dir@.service.in

@@ -10,6 +10,7 @@
 [Unit]
 Description=/run/user/%i mount wrapper
 Documentation=man:user@.service(5)
+After=systemd-user-sessions.service
 StopWhenUnneeded=yes
 
 [Service]