bug#13949: 24.3.50; `fill-paragraph' should not always put the buffer as modified

[Dani Moncayo]

>> This seems a bug, since step #4 didn't make any change in the buffer
>> contents (the paragraph was already filled).
>
> Step #4 does change the buffer, because M-q doesn't know whether the
> paragraph is already filled, so it fills it anew each time.
>
> Emacs always behaved like that.

Ah, Ok.

Well, since the `fill-paragraph' command at step #4 leaved the buffer
with the same contents, flagging the buffer as modified was
unnecessary in this case.

In general, I think that a command should flag the buffer as modified
only when the buffer contents at the end of the command were different
from the contents at the beginning of that  same command.

But, I don't know complex is that to implement, and perhaps that
complexity outweighs the benefits.

I'll let you (maintainers) to judge this.  Feel free to close this bug
if the change isn't worth the trouble.

Thanks.

-- 
Dani Moncayo