avoid/delayed service reload on upgrade

[Fernando Toledo <ftoledo@docksud.com.ar>]

Hi all!
I packaging mdm[1], a fork from gdm for Huayra[2] (a derivative Debian
distribution based on jessie).
Our package is based on upstream debian directory with some customized
settings[3] to work better with our distro.

At this time, MDM work perfect in our system.
Now, i focused on get full working with systemd (and better plymouth
integration).
If i use systemd (not sysvinit) for start the service, i get a kill to
xserver when upgrading the package from one version to another.

Im search the better way (if is possible) to avoid the restart of the
service when uprading. maybe fixing the .service file?

I think that systemd receive a "reload or restart" message to the daemon
when upgrading that kill the actual xserver instance.

This produce two problems, if you try to upgrade from x desktop, first
kill entire xserver, second break the dpkg database because the package
is not correctly finish the installation.

[1]https://github.com/linuxmint/mdm
[2]http://huayra.conectarigualdad.gob.ar
[3]https://github.com/HuayraLinux/huayra-mdm.

Thanks!
-- 
Fernando Toledo
Dock Sud BBS
http://bbs.docksud.com.ar
telnet://bbs.docksud.com.ar