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

[Óscar Fuentes]

Drew Adams <drew.adams@oracle.com> writes:

>> The tools must be adapted to the mental model of their users.
>
> Yes, and:
>
> 1. Different users have different use cases and different mental
>    models.
>
> 2. The same user has different mental models, depending on the
>    current context.
>
> 3. Code too, not just users, needs to be able to detect buffer
>    changes.
>
> 4. There are different kinds of buffer changes.  It would be
>    good to have ways to detect these as such.

Please provide an example were the user would benefit from marking the
buffer as modified after applying a fill-paragraph operation that
doesn't make a difference on the buffer contents.