bug#41934: reverse-region no longer works

[Eli Zaretskii]

> From: Richard Copley <rcopley@gmail.com>
> Date: Thu, 18 Jun 2020 18:59:21 +0100
> Cc: 41934@debbugs.gnu.org
> 
> On Thu, 18 Jun 2020 at 18:52, Richard Copley <rcopley@gmail.com> wrote:
> > On Thu, 18 Jun 2020 at 18:42, Eli Zaretskii <eliz@gnu.org> wrote:
> > Thanks,
> > No, that fails on this example [...]
> 
> How's this?

Looks good, but what if beg and end are on the same line (at the point
where you added the test)?  Does that not warrant the error message?