The following .cfg file produces an error:
[sdist] manifest = MANIFEST no-defaults = 1 keep-tree = 1 formats=bztar,gztar,tar,zip,ztar
... error: error in setup.cfg: command 'sdist' has no such option 'keep-tree'
Looks as if the config file parser doesn't like options with embedded hyphens (or maybe it's just me not knowing how to pass the options ?).