bug#37820: 25.2; xref using etags incorrect case fold during completion

[Eli Zaretskii]

> Cc: 37820@debbugs.gnu.org, Eli Zaretskii <eliz@gnu.org>
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Fri, 17 Jan 2020 04:15:07 +0300
> 
> Eli, is this patch okay for emacs-27?
> 
> On the one hand, the issue seems minor-ish.
> 
> On the other, it's a backward compatibility problem. And the patch must 
> be pretty safe because it's basically additive: the only real change is 
> to xref--read-identifier, and it calls 
> xref-backend-identifier-completion-ignore-case which will default to the 
> current behavior for all backends except etags.

Can you tell what is the difference in user-facing behavior due to
this change?  I'm not sure I understand that looking at the patch.

Thanks.