I have a similar problem with pywin32.  I've described this over on
http://allmydata.org/trac/tahoe/ticket/756 (if pywin32 has been manually
installed, setuptools still doesn't detect it), but here is the minimal test case:

Put the following into a file named {{{setup.py}}} in a new empty directory:

{{{
import pkg_resources
if pkg_resources.require("pywin32"):
    print "Yes, pkg_resources says that pywin32 is already installed."
from setuptools import setup
setup(name='mindeponpywin32', install_requires=['pywin32'])
}}}

Make sure pywin32 is installed (by executing the installer for it and clickety
clickety clicking).

Then run the following command:

{{{
$ python ./setup.py develop
}}}

It will say something like:

{{{
Yes, pkg_resources says that pywin32 is already installed.
running develop
}}}
...
{{{
Processing dependencies for mindeponpywin32==0.0.0
Searching for pywin32
Reading http://pypi.python.org/simple/pywin32/
Reading http://sf.net/projects/pywin32
Reading http://sourceforge.net/project/showfiles.php?group=78018
No local packages or download links found for pywin32
error: Could not find suitable distribution for Requirement.parse('pywin32')
}}}