Hm... now I see that link is very misleading... it opens a blog post, and then only a few seconds later jumps to the comment. So now I'll paste the comment here, to avoid misunderstandings:

Python3.6.0 (now in 2017). I start IDLE, and write

>>> def deco(f):
        import functools
        @functools.wraps(f)
        def ret(*args, **kw):
                return f(*args, **kw)
        return ret

>>> @deco
def f(n, k):
        return n + k*2

>>> f(

And get a tooltip (*args, **kw) instead of (n, k). I guess this is a bug.