In every Tryton source file there is at the beginning
This file is part of Tryton. The COPYRIGHT file at the top level of
this repository contains the full copyright notices and license terms.
and indeed the source distribution has a ‘COPYRIGHT’ file.
However it seems that the binaries (the wheel files on pypi) do not include this file.
A distro package such as a Debian package also lack this file, but it’s less annoying since they generate their copyright file derived from the different parts integrated in the package (the latest Debian is not up-to-date with the COPYRIGHT Tryton file though, their file was created a long time ago probably.
Given that I don’t know any magical way to include the COPYRIGHT file into the trytond subdirectory with setuptools/wheel and the like, the best can could be done IMO is to add to the setup.cfg file:
that will copy the COPYRIGHT file to the trytond-4.4.0.dist-info directory under dist-packages or site-packages (but with the name ‘LICENSE.txt’).
That’s not perfect, far from it, but that’s the best I can see.