mpz reuse test takes too much time

[Marc Glisse]

On Sat, 3 Dec 2016, Niels Möller wrote:

>> Since s and t may get swapped depending on the values of a and b, you
>> cannot really support t==NULL without supporting s==NULL. You may
>> prefer not documenting it though...
>
> I think that's an implementation detail that shouldn't be documented.
> Can we just strike it from the docs? (And possibly back it up with an
> ASSERT at function entry).

Sure, go ahead. I was only interested in handling g == NULL, and took the 
chance to document s == NULL for completeness, but I probably shouldn't 
have.

-- 
Marc Glisse