I simplified the implementation a bit more because @mauritsvanrees pointed me to an easier way which even sould prevent a warning during the release if there are directories which do not contain any Python code.

Thank you for reviewing this PR. 😃

Since all packages in the zopefoundation org have a src layout, we could also use automatic package discovery.

That means these lines (plus the import of find_namespace_packages) could be removed:

    packages=find_namespace_packages('src'),
    package_dir={'': 'src'},

I tried it out in Products.GenericSetup by building a wheel (in my case ../../bin/zopepy -m build .), unzipping it, and then comparing. I saw no differences in the included files using the setup.py of current master, or the one after running the current script, or after removing those extra lines.

Pull Request Test Coverage Report for Build 13265640074

Details

• 0 of 66 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.7%) to 16.634%

Totals
Change from base Build 13132027896:	-1.7%
Covered Lines:	166
Relevant Lines:	800

💛 - Coveralls

Since all packages in the zopefoundation org have a src layout, we could also use automatic package discovery.

That means these lines (plus the import of find_namespace_packages) could be removed:

    packages=find_namespace_packages('src'),
    package_dir={'': 'src'},

Thank you for investigating: I did this in #305.