spec checking goes awry when replacing a class

Best explained by example perhaps:

mwh@grond:trunk$ cat t.py
class C(object):
 def __init__(self, a): pass
 def __call__(self, *args): pass

import mocker
m = mocker.Mocker()
m_C = m.replace(C, passthrough=False)
m_C(mocker.ARGS, mocker.KWARGS)
m.replay()
C(a=1)
mwh@grond:trunk$ python t.py
Traceback (most recent call last):
  File "t.py", line 10, in <module>
    C(a=1)
  File "/home/mwh/canonical/repos/mocker/trunk/mocker.py", line 1221, in __call__
    return self.__mocker_act__("call", args, kwargs)
  File "/home/mwh/canonical/repos/mocker/trunk/mocker.py", line 1197, in __mocker_act__
    raise AssertionError(os.linesep.join(message))
AssertionError: [Mocker] Unmet expectation:

=> m_C(ARGS, KWARGS)
 - Run: m_C(a=1)
 - Specification is __call__(*args): unknown kwargs: a

I think that the basic problem is that, if you see a call to an object, accessing __call__ on that object is not actually the right thing to do in all cases! Accessing the __call__ on the type is closer, but for types its worth making a special case and checking the signature of __init__ I guess.