OTOH, xml.etree.cElementTree.Element in Python 3.2 and earlier has never been pickleable, either.
Python 3.2.3+ (3.2:24499eebbc2f, Oct 10 2012, 13:54:45)
[GCC 4.6.3] on linux2
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>>> from xml.etree.cElementTree import Element
>>> repr(Element)
'<built-in function Element>'
>>> import pickle
>>> pickle.dumps(Element('foo'))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
_pickle.PicklingError: Can't pickle <class 'Element'>: attribute lookup builtins.Element failed