bug#31073: 27.0.50; query-replace undo might change the word case

[Eli Zaretskii]

> From: Tino Calancha <tino.calancha@gmail.com>
> Cc: 31073@debbugs.gnu.org, Juri Linkov <juri@jurta.org>
> Date: Sun, 08 Apr 2018 10:14:01 +0900
> 
> Juri Linkov <juri@jurta.org> writes:
> 
> >> The undo feature shouldn't change the case; it must return
> >> to the original words.
> >>
> >> emacs -Q
> >> <
> >> M-% t RET FOO RET SPC SPC SPC SPC U
> >> ;; The first line shows upcase 'T' at several positions, for instance
> >> ;; it shows 'TexT', originally shown as 'text'.
> >
> > Good catch!  This means we should have more test coverage.  Thanks.
> Eli,
> 
> this feature was introduced for Emacs-26 release.  Should the fix go
> into that branch (Emacs-26)?

It's too late for Emacs 26.1.  For the other 26.x, I'd need to see the
patch first.

Thanks.