bug#13949: 24.4.1; `fill-paragraph' should not always put the buffer as modified

[Óscar Fuentes]

Dmitry Gutov <dgutov@yandex.ru> writes:

> Hashes have collisions (and md5 is a bit famous for them). So in
> principle, I don't think using a hash is a good choice in this case.
>
> Either way, you'd have to keep the original string around, to compare
> against if the hashes match.

Dmitry, it would be absolutely glorious if we ever find a md5 collision
among a piece of text and the result of applying fill-paragraph to it. I
would demand to be credited by the feat :-)