The first argument can be remedied by creating a new method that deals with that (something like `def _new_init(cls)`, and passing the `cls` as argument).

The third argument is not really an argument - there is a bug that needs a precedent to be solved.

Concerning the second argument, I think it is only problematic when pickling in a new version of python and unpickling in an old one, and not vice versa (because the reduction from previous versions calls __init__). In the old->new direction, there wouldn't be much of a problem because the worst thing that happens, is that this bug could occur.
If that doesn't satisfy you, I hope that this change can be made in the future, when a version that allows such a lack of backward-compatibility is released.