Calling the unicode function on a proxy object, doesn't use the proxi-ed
object's __unicode__ method, but its __str__ method.

>>> class A(object):
...   def __str__(self):
...     return "str"    
...   def __unicode__(self):
...     return "unicode"    
...                         
>>> a = A()
>>> unicode(a)
u'unicode'
>>> import weakref
>>> b = weakref.proxy(a)
>>> unicode(b)
u'str'

I expected the last result to be u'unicode'. I did get u'unicode' in
Python 2.5 (but not in 2.6).