There's been a previous post (Tarek, "Fixing the mess in sdist/egg_info") about the fact that setuptools fails due to a circular dependency:

distutils.sdist.run() -> setuptools.build_py.data_files -> setuptools.egg_info.run() -> distutils.sdist.add_defaults() -> setuptools.build_py.data_files -> etc

Actually I'm working packaging sphinx and it fails for this reason. Has anything moved to fix this problem?

Regards, Antonio