Problem:
In your MANIFEST.in, you have a line like
graft src/
but when you run
python setup.py sdist
some file in src is not included in the archive
Solution:
This is due to the slash at the end of src/! The slash works fine on Linux, but on Windows, backslashes are used to separate directory names. You can just remove the slash after src, it doesn’t serve any purpose on Windows or Linux:
graft src
After that, retry and you should see your file being included in the sdist archive.