[Pkg-utopia-maintainers] Bug#982853:

[Michael Schaller]

I was able to reproduce the issue on vanilla Debian testing by purging
the `dbus-user-session` package, which is currently blocked in our
fleet for Reasons (TM).

Reproduction instructions:

1) Install VM via the Debian stable `mini.iso` (Debian testing was
broken) with all the defaults except the `software to install`
selection was completely empty, particularly no desktop environment.
   Image source was:
https://deb.debian.org/debian/dists/stable/main/installer-amd64/current/images/netboot/mini.iso

2) Update to Debian testing.
   $ sudo sed -i 's/buster/testing/g' /etc/apt/sources.list
   $ sudo sed -i '/security/d' /etc/apt/sources.list
   $ sudo apt update
   $ sudo DEBIAN_FRONTEND=noninteractive apt -o
Dpkg::Options::=--force-confnew -o Dpkg::Options::=--force-confdef
dist-upgrade
   $ sudo reboot

3) Install GDM and Cinnamon
   $ sudo apt install gdm3 cinnamon
   $ sudo reboot

4) Log into Cinnamon from GDM
   Note: pipewire succeeds to start.

5) Remove dbus-user-session
   $ sudo apt purge dbus-user-session
   $ sudo reboot

6) Log into Cinnamon from GDM
   Note: pipewire fails to start.