At the top of debian/rules:

# This file is PUBLIC DOMAIN.
#
# Copyright © 2001,2003, 2009, 2010 Jeff Bailey, Jordi Mallach.

So, what is the actual copyright on the files for building the Debian
packages?  Are they in the public domain (as stated)?  Are they under
some flavor of copyright?

Things *cannot* be both in the public domain and under copyright.  They
can only be in one situation or the other.  I'm guessing Jeff Bailey
created the packaging files and put them into the public domain.
Subsequently Jordi Mallach took over maintaining the package and may or
may not wish to own copyright on the files.  In this situation it could
say "Created by Jeff Bailey in 2001", but it certainly appears Jeff
Bailey relinquished all copyright.

Does Jordi Mallach actually wish to own the copyright on the files?  Do
you instead wish to emulate Jeff Bailey and put them FULLY in the public
domain?

The debian/rules file has since been updated. See the package's
debian/copyright file for copyright info, which appears to be up to
date.