0.9a was intending to be a prior version of 0.9. According

http://www.python.org/dev/peps/pep-0386/ it was wrong.
Update the version with an incremented extraversion number.

setup.py

 from setuptools import setup, find_packages
 import sys, os
 
-version = '0.9a'
+version = '0.9.1'
 
 setup(name='xml_marshaller',
       version=version,