Here's a first attempt at a patch, if someone'd take a look.

On Sun, Apr 8, 2018 at 9:07 AM, Stefan Monnier <monnier@iro.umontreal.ca>
wrote:

> > I'd *guess* the fix would be applied in `cl--parse-loop-clause`?
> > Perhaps Stefan could give some pointers?
>
> Maybe I'm one of the least unknowledgeable about this code, but it's
> still pretty obscure for me, sorry,
>
>
>         Stefan
>
>
>