The first half of the Validator.PostalCode class is
missing from CVS.
It was obviously deleted by accident, leaving just the
following fragment in Validator.py:
_postalCodeRE = re.compile(r'^\d\d\d\d\d(?:-\d\d\d\d)?$')
if not kw.setdefault('messages',
kw['messages']['invalid'] = 'Please enter a zip
code (5 digits)'
return Regex(_postalCodeRE, **kw)