FormEncode for Python

Attempt to use FieldStorageUploadConverter with schema
validation to process file uploads yields an error:

File
"d:\projects\3rd-party\turbogears\turbogears\controllers.py",
line 110, in validate
kw.update(form.validate(value))
File
"d:\projects\3rd-party\turbogears\turbogears\widgets\forms.py",
line 865, in validate
return self.validator.to_python(value, state)
File
"c:\python24\lib\site-packages\formencode-0.4-py2.4.egg\formencode\api.py",

line 308, in to_python
value = tp(value, state)
File
"c:\python24\lib\site-packages\formencode-0.4-py2.4.egg\formencode\schema.p
y",
line 132, in _to_python
new[name] = validator.to_python(value, state)
File
"c:\python24\lib\site-packages\formencode-0.4-py2.4.egg\formencode\api.py",

line 297, in to_python
if not value and value != 0:
File "C:\Python24\lib\cgi.py", line 625, in __len__
return len(self.keys())
File "C:\Python24\lib\cgi.py", line 601, in keys
raise TypeError, "not indexable"
TypeError: not indexable