fix broken config for GenericModel

Summary: D42760349 (https://github.com/facebookresearch/pytorch3d/commit/9540c29023c2b6bb53e5a26a5e7a9d34ce88e9b1) (make Module.__init__ automatic) didn't account properly for inheritance.

Reviewed By: shapovalov

Differential Revision: D42834466

fbshipit-source-id: 53ee4c788985c1678ad905c06ccf12b2b41361e9

pytorch3d/implicitron/tools/config.py

@@ -944,7 +944,7 @@ def _fixup_class_init(some_class) -> None:
         torch.nn.Module.__init__(self)
         getattr(self, _DATACLASS_INIT)(*args, **kwargs)
 
-    assert not hasattr(some_class, _DATACLASS_INIT)
+    assert _DATACLASS_INIT not in some_class.__dict__
 
     setattr(some_class, _DATACLASS_INIT, some_class.__init__)
     some_class.__init__ = init