bug#23484: 25.1.50; undo doesn't work properly in xref-query-replace-in-results

[Juri Linkov]

> However, how would you allow doing this *without* losing the ability to
> replace the matches and just the matches? That should be the
> default choice.

So I see your aim is to use regexp replacements without regexps,
i.e. with only a list of region boundaries like is used by
region-noncontiguous-p in perform-replace.  I guess this could be
achieved with more hacking in real-match-data (maybe to use a layer
like replace-match-data).