upgrading from python 2.3.4 to 2.3.5rc1 I got this
error on a module that was working correctly


  File "../Field.py", line 203, in copy
    properties = deepcopy(cdict)
  File "/usr/lib/python2.3/copy.py", line 191, in deepcopy
    y = copier(x, memo)
  File "/usr/lib/python2.3/copy.py", line 285, in
_deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
  File "/usr/lib/python2.3/copy.py", line 200, in deepcopy
    copier = _getspecial(cls, "__deepcopy__")
  File "/usr/lib/python2.3/copy.py", line 66, in
_getspecial
    for basecls in cls.__mro__:
AttributeError: __mro__