"setup.py test" throwing "ValueError: Empty module name"

Running 'setup.py test' suddenly started throwing a ValueError:

$ /usr/bin/python ./setup.py test
running test
running egg_info
writing pyVBox.egg-info/PKG-INFO
writing top-level names to pyVBox.egg-info/top_level.txt
writing dependency_links to pyVBox.egg-info/dependency_links.txt
reading manifest file 'pyVBox.egg-info/SOURCES.txt'
writing manifest file 'pyVBox.egg-info/SOURCES.txt'
running build_ext
Traceback (most recent call last):
  File "./setup.py", line 17, in
    url = "http://github.com/von/pyVBox"
...snip...
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/unittest.py", line 576, in loadTestsFromName
    module = __import__('.'.join(parts_copy))
ValueError: Empty module name

Poking around with pdb, it turns out it was because the name argument to loadTestsFromName():

(Pdb) print parts_copy
['test', '', '#VirtualMachineTests']
(Pdb) print name
test..#VirtualMachineTests

Which turns out to be caused by a Emacs autosave file. I had unsaved changes in my Emacs buffer. Once I saved them, the autosave file went away and 'setup.py test' ran fine.

Obviously some deeper problem here with setup.py tripping over these files.