Setdefault bypasses __setitem__

[Ron Garret]

Is this a bug or a feature?

class mydict(dict):
   def __setitem__(self, key, val):
     print 'foo'
     dict.__setitem__(self, key, val)

>>> d=mydict()
>>> d[1]=2
foo
>>> d.setdefault(2,3)
3

rg