[Python] distutils, cygwin, 'not a regular file'

So, what is not a regular file about this? Is there any way to find out
which files are being considered irregular?

$ uname -a
CYGWIN_NT-6.0-WOW64 pwatson 1.7.7(0.230/5/3) 2010-08-31 09:58 i686 Cygwin

$ cat setup.py

from distutils.core import setup

setup(
name='xlsexport',
version='0.3',

py_modules=['xlsexport']
)
20:47 pwatson [ pwatson:/cygdrive/c/Users/pwatson/bin/xlsexport] 12
$ python setup.py sdist
running sdist
warning: sdist: missing required meta-data: url
warning: sdist: missing meta-data: either (author and author_email) or
(maintainer and maintainer_email) must be supplied
reading manifest file 'MANIFEST'
creating xlsexport-0.3
making hard links in xlsexport-0.3...
' not a regular file -- skipping
' not a regular file -- skipping
' not a regular file -- skipping
tar -cf dist/xlsexport-0.3.tar xlsexport-0.3
gzip -f9 dist/xlsexport-0.3.tar
removing 'xlsexport-0.3' (and everything under it)