app Engine + cssutils problem

[xcession]

I'm investigating google app engine for a little css-related project,
but am having trouble doing the simplest things and I'm stumped as to
why.

I've gone through the Guestbook example and have modified it only a
little thus:

<snip>
import os
import codecs
import cssutils

from google.appengine.ext.webapp import template
from google.appengine.ext import webapp
from google.appengine.ext.webapp.util import run_wsgi_app

class MainPage(webapp.RequestHandler):

def get(self):
css = '''
body {
color: blue;
font: normal 100% sans-serif;
}
p {
color: green;
font-size: 2em;
}
.x {
color: black;
}
'''
sheet = cssutils.parseString(css)

</snip>

But when I run it, i'm getting the errors:

Traceback (most recent call last):
File "C:\Program Files\Google\google_appengine\google\appengine\ext
\webapp\__init__.py", line 501, in __call__
handler.get(*groups)
File "c:\test\helloworld.py", line 31, in get
sheet = cssutils.parseString(css)
File "c:\test\cssutils\__init__.py", line 150, in parseString
return CSSParser().parseString(*a, **k)
File "c:\test\cssutils\parse.py", line 95, in parseString
cssText = codecs.getdecoder('css')(cssText, encoding=encoding)[0]
File "C:\test\cssutils\codec.py", line 200, in decode
if _encoding == "css":
TypeError: 'NoneType' object is not callable

I'm on windows, python 2.5, cssutils-0.9.6a3. I've had to copy the
cssutils and encutils folder from site-packages into my c:\test
folder, as per google app engine instructions.

If I remove all the app-engine specifics, basically ending up with
just the imports and a "main()" function in the file, then run it on
its own with python, it works fine.

I'm a python noob anyway, so this could be something embarrassingly
simple, but if so I can't see it!

Hope you can help

[xcession]

Some further googling suggests that the codecs lib isn't supported by
GAE as they've rolled their own. Is this actually an issue or just
someone else's conjecture?