The correct process is asking the author or the upstream to set a license.
After that you should repacked the software for any help on that take a quick look at:
Hi François,
In my point of view, if the last contributors didn't mentioned anything about license they are in according of the public domain. And the additional question i think you don't need to asking to the the authors of debian/* license packing because its in Public Domain.
Em dom, 19 de jul de 2020 12:31, François Mazen <
francois@mzf.fr> escreveu:
Dear Mentors,
I'm trying to reintroduce the photoprint package [1], and I'm rewriting
the debian/copyright file to comply with dep5.
The initial license for the files in debian/* folder is "public
domain". Then many other contributors made changes to the debian folder
files, but the copyright file was not updated [2]. So I don't know the
license of these new contributions. Are they in "public domain" by
default? or the package license (GPL-2+)?
Additional question: for "public domain" files, is it possible to
change license to GPL-2+ without explicitly asking the authors?
Thanks,
François
[1]: https://tracker.debian.org/pkg/photoprint
[2]:
https://salsa.debian.org/mzf/photoprint/-/blob/e78dd4b4ee5111ae002b6514cd72fb4f7b9c9e91/debian/copyright