bug#17343: 24.2; Exponential growth of files using raw-mode

[Stefan Monnier]

>   1. Save the following line in a file "testAccentsMinimal.txt"

>   Nà¥

†

à¤

††

à¥

†

>   2. Repeatedly, 

>      0) measure the size of the file (wc -c testAccentsMinimal.txt); 
>      1) open emacs loading the file (emacs -q testAccentsMinimal.txt);
>      2) insert and delete a character in it (manually);
>      3) save it selecting the suggested raw encoding (manually);

I cannot reproduce this. At this step, Emacs just saves the
file silently.  And the file keeps its size constant.
I tried with Debian's Emacs-24.3 and Emacs-23.4 as well as with the
current pretest (and using "-Q" rather than "-q").

> I think that I signaled this bug 1 year ago in Emacs 23 and was answered
> at the time that this would be solved by the next version (24), but it
> occured to me recently that this undesirable behavior was still there :(

We're pretesting 24.4, so hopefully we can finally crush this one for
24.4.


        Stefan