  basepython = python3.2
  deps = https://www.djangoproject.com/download/1.5c1/tarball/
         https://github.com/alex/django-filter/archive/master.tar.gz
  
  [testenv:py2.7-django1.5]
  basepython = python2.7
  deps = https://www.djangoproject.com/download/1.5c1/tarball/
         django-filter==0.5.4
 
</s>
       defusedxml==0.3
  basepython = python3.2
  deps = https://www.djangoproject.com/download/1.5c1/tarball/
         https://github.com/alex/django-filter/archive/master.tar.gz
       defusedxml==0.3
  
  [testenv:py2.7-django1.5]
  basepython = python2.7
  deps = https://www.djangoproject.com/download/1.5c1/tarball/
         django-filter==0.5.4
keep keep add keep keep keep keep keep
 defusedxml for security fix.

As per:
http://blog.python.org/2013/02/announcing-defusedxml-fixes-for-xml.html
tox.ini