bug#17388: 24.4.50; REGRESSION: Ediff - 1) wrong face, 2) incorrect diffing

[Drew Adams]

> > There should be EITHER, (a) as previously, NO fine diffs shown for
> > other than the current diff OR (b) CORRECT (helpful) fine diffs
> > shown for the non-current diffs.
> 
> Ediff's "fine diffs" are word-granular.  That is, Ediff breaks each
> line into "words", then passes the result to the Diff program for
> comparisoon, and reflects the results with different faces.  AFAIR,
> this has always been that way.

OK, so you are saying that Emacs has silently changed to (b) from (a),
and the way it does fine diffs corresponds to what is shown.  So be it.

> > > I see both of these problematic highlightings on GNU/Linux builds from
> > > both the trunk (bzr 117042) and the emacs-24 branch (bzr 117049).
> 
> I can confirm that too, but (a) I don't think the 2nd issue
> constitutes a "problem" (see above), and (b) it is definitely not a
> "REGRESSION", because older Emacsen behaved the same wrt fine diffs
> inside a line.

It is a change in behavior wrt older Emacsen, which do not show fine
diffs within the non-current diffs.  Regression or improvement - we
can have different opinions.  (BTW, I see nothing in NEWS about this
behavior change.)

But more importantly, "REGRESSION" in the subject line is for the bug
report, and #1 is the more serious part: removing diff highlighting
from part of a diff gives the impression that that unhighlighted text
is not different.