> Bare excepts are syntactic sugar for `except BaseException`.

I'm guessing that a `3to4` script would be provided which replaces bare `except:` with `except BaseException:`. We have the experience of `2to3` to draw on with regards to how that might play out.

EDIT: Haha, I now see that this PEP proposes a change without advancing the major version. That surprises me.