mock.call_args can be both equal to and not equal to another object:

>>> m = Mock()
>>> m(1,2)
<Mock name='mock()' id='4483976016'>
>>> m.call_args
call(1, 2)
>>> m.call_args == call(1,2)
True
>>> m.call_args != call(1,2)
True

This appears to be a recent regression - it repros on trunk, but not on 3.3 or 2.7 with mock 1.3.0.