Accidentally passing package_data a str value triggers error on Windows but not Linux

As part of https://github.com/greenelab/manubot/pull/51, I specified the package_data argument of setuptools.setup() in our setup.py:

    # Specify additional patterns to match files
    package_data={
        'manubot': 'cite/*.lua',
    },

The Linux Travis CI build passes, but the Windows AppVeyer builds error when attempting pip install .. Here is the error:

%CMD_IN_ENV% pip install .
Processing c:\projects\manubot
    Complete output from command python setup.py egg_info:
    running egg_info
    creating pip-egg-info\manubot.egg-info
    writing pip-egg-info\manubot.egg-info\PKG-INFO
    writing dependency_links to pip-egg-info\manubot.egg-info\dependency_links.txt
    writing entry points to pip-egg-info\manubot.egg-info\entry_points.txt
    writing requirements to pip-egg-info\manubot.egg-info\requires.txt
    writing top-level names to pip-egg-info\manubot.egg-info\top_level.txt
    writing manifest file 'pip-egg-info\manubot.egg-info\SOURCES.txt'
    c:\python36\lib\distutils\dist.py:261: UserWarning: Unknown distribution option: 'long_description_content_type'
      warnings.warn(msg)
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-akczu3gv\setup.py", line 75, in <module>
        'manubot': 'cite/*.lua',
      File "c:\python36\lib\site-packages\setuptools\__init__.py", line 129, in setup
        return distutils.core.setup(**attrs)
      File "c:\python36\lib\distutils\core.py", line 148, in setup
        dist.run_commands()
      File "c:\python36\lib\distutils\dist.py", line 955, in run_commands
        self.run_command(cmd)
      File "c:\python36\lib\distutils\dist.py", line 974, in run_command
        cmd_obj.run()
      File "c:\python36\lib\site-packages\setuptools\command\egg_info.py", line 278, in run
        self.find_sources()
      File "c:\python36\lib\site-packages\setuptools\command\egg_info.py", line 293, in find_sources
        mm.run()
      File "c:\python36\lib\site-packages\setuptools\command\egg_info.py", line 524, in run
        self.add_defaults()
      File "c:\python36\lib\site-packages\setuptools\command\egg_info.py", line 560, in add_defaults
        sdist.add_defaults(self)
      File "c:\python36\lib\site-packages\setuptools\command\py36compat.py", line 34, in add_defaults
        self._add_defaults_python()
      File "c:\python36\lib\site-packages\setuptools\command\sdist.py", line 134, in _add_defaults_python
        for _, src_dir, _, filenames in build_py.data_files:
      File "c:\python36\lib\site-packages\setuptools\command\build_py.py", line 66, in __getattr__
        self.data_files = self._get_data_files()
      File "c:\python36\lib\site-packages\setuptools\command\build_py.py", line 83, in _get_data_files
        return list(map(self._get_pkg_data_files, self.packages or ()))
      File "c:\python36\lib\site-packages\setuptools\command\build_py.py", line 95, in _get_pkg_data_files
        for file in self.find_data_files(package, src_dir)
      File "c:\python36\lib\site-packages\setuptools\command\build_py.py", line 114, in find_data_files
        return self.exclude_data_files(package, src_dir, files)
      File "c:\python36\lib\site-packages\setuptools\command\build_py.py", line 198, in exclude_data_files
        files = list(files)
      File "c:\python36\lib\site-packages\setuptools\command\build_py.py", line 234, in <genexpr>
        for pattern in raw_patterns
      File "c:\python36\lib\distutils\util.py", line 125, in convert_path
        raise ValueError("path '%s' cannot be absolute" % pathname)
    ValueError: path '/' cannot be absolute

In summary, this line in distutils.util.convert_path is throwing the following error:

ValueError: path '/' cannot be absolute

So at some point, it seems that the package_data relative path is converted to absolute triggering this error. Any advice on how to resolve this issue would be greatly appreciated! This is occurring with pip-18.0 in Python 3.6 & 3.7.

[aschmied]

@dhimmel according to the docs here the values in the package_data dict should be arrays. Try

package_data={
    'manubot': ['cite/*.lua'],
}

[dhimmel]

Looks like the validation of the package_data and exclude_package_data fields occurs here:

https://github.com/pypa/setuptools/blob/3adda966e2e76ad59cf79fd8bdeab77fb11d308f/setuptools/dist.py#L307-L322