The two ways of getting a parametrised Callable have inconsistent __args__:

    >>> import collections.abc, typing
    >>> typing.Callable[[int, int], int].__args__
    (int, int, int)
    >>> collections.abc.Callable[[int, int], int].__args__
    ([int, int], int)

I discovered this while working on PEP 585 support in Hypothesis [1], where it is easy enough to work around but carries a potentially serious performance cost - the list means we cannot use the type as a cache key for non-`...` argument types.  

https://bugs.python.org/issue40494 and https://bugs.python.org/issue40398 may be related.

[1] https://github.com/HypothesisWorks/hypothesis/pull/2653