I concur with Martin: setup() should disallow an empty string as a package, because an empty string is not a valid Python package name.

Regarding Jim's comment that the stripping should be smarter, I'd like to point out that package_dirs must only contain platform-independent directory names, and if anything else is included, it will produce an error when the build_py command is initialized, as 'convert_path' is called on the paths in question.  Thus, they can never contain absolute paths or end in a trailing /.

Thus, the only problem here is that packages is allowed to contain empty strings, which it makes no sense to include.