I'm trying to build a package which has some files under /etc that are not configuration. They are included in the conffiles automatically even if I create an empty package.conffiles in the debian directory.
How can I stop dh_installdeb from doing that?
You could provide your own debian/conffiles files only listing actual configuration files to be installed. With that, debhelper won't touch that file at all.
However, I can't quite see why you'd even want that. If the files are not configuration files, the user won't edit them, so none of the automatic conffile handling will get in your way on upgrades. Also, if they're not actually config files, I'd highly recommend to simply install them to a place other than /etc, avoiding your issue as well.