The test complains[1][2] that
Failed to start message bus: Failed to bind socket "/run/dbus/system_bus_socket": No such file or directory
In 639e5401ff51d4c0075b5ceffcbdbfec64c67db3, the dbus socket dir is set
to `/run/dbus`; in the test vm `/var/run/dbus` is used, but the standard
`/run -> /var/run` link is typically not created until stage 2 init, not
in the minimal init used here. Thus, dbus fails to run within the test
environment . Fix by changing `/var/run/dbus` to simply `/run/dbus`.
[1]: https://hydra.nixos.org/build/42534725
[2]: https://hydra.nixos.org/build/42523834
c86fe2224e