bug#32991: 27.0.50; diff-auto-refine-mode a no-op

[Charles A. Roelli]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Date: Mon, 08 Oct 2018 17:00:31 -0400
> 
> >>     * lisp/vc/diff-mode.el: Perform hunk refinement from font-lock
> > Looks like this commit makes diff-auto-refine-mode a no-op, since
> > hunks are now always refined.  Is that the intention?
> 
> Yes.  Of course, it depends on the value of diff-font-lock-refine.

Ok.  In that case, do we still need diff-auto-refine-mode?

> > Also, with automatic refinement always on, does the following part of
> > diff-mode.el still require refining the hunk?
> 
> I believe this is the same question.

I'm not sure I understand.  If the default value of
diff-font-lock-refine results in hunks being automatically refined by
font-lock, why should the navigation function possibly re-do the
refining already done by font-lock?