bug#25105: 26.0.50; diff navigation is broken

[Dmitry Gutov]

On 06.01.2017 11:03, Tino Calancha wrote:

> > Another alternative is to have a customizable option which will let
> > users decide what behavior they want.
> That would be OK.  I would suggest to set this option nil by default,
> i.e., disable the new feature by default for backward compatibility.

If separating behavior into two parts that are controlled by a switch 
would be feasible (I'm not sure), it might be okay.

However, the new behavior also fixes what was undoubtedly a problem:

When point is a bob in a diff-mode buffer, `C-c C-a' applies the first 
hunk, and then stops at its beginning (in Emacs 25 and earlier).

We would then give up on that fix, whereas I'd prefer to have a solution 
eventually, if not now. But if we do, I estimate we might have the "old 
fixed" behavior encroach on the "new different" behavior in certain 
respects, making the code even more complex.

I've honestly thought that Dima's patch's main purpose was to fix that 
bug. And everything else we now complain about are just implementation's 
side-effects.