2011/7/16 Nick Coghlan <report@bugs.python.org>:
>
> Nick Coghlan <ncoghlan@gmail.com> added the comment:
>
> It also makes it clear to users whether they've just run up against a
> limitation of the implementation they're using or whether what they've
> written is genuinely illegal code. They are NOT the same thing.
> Attempting to conflate them into one exception for the mere sake of
> not adding a new exception type is a false economy. Take it to
> python-dev if you want, but I will strongly oppose this check going in
> with it raising an ordinary SyntaxError instead of a new subclass.

Why would it matter to users what variety of limitation they're
running up against? As I said, they're still going to have to change
their code.