Bug#988337: weston: Fails to start with `environment variable XDG_RUNTIME_DIR is not set.`

[Paul Menzel <pmenzel@molgen.mpg.de>]

Package: weston
Version: 9.0.0-4
Severity: normal


Dear Debian folks,


Installing a minimal Debian system, then installing Weston with `sudo 
apt install weston`, then trying to start it, it fails to start (even 
with the user added to the group `weston-launch`, Weston fails to start 
and shows the error below.

    fatal: environment variable XDG_RUNTIME_DIR is not set.
    Refer to your distribution on how to get it, or
    http://www.freedesktop.org/wiki/Specifications/basedir-spec
    on how to implement it.

the error below is shown.

`systemd-logind.service` is running, but `loginctl list-sessions` does 
not show anything.

Installing `libpam-systemd` gets that working.


Kind regards,

Paul