bug#23980: 25.0.95; Events put in `unread-command-events' can be wrongly handled

[Eli Zaretskii]

> Cc: 23980@debbugs.gnu.org
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Wed, 21 Feb 2018 12:47:20 +0200
> 
> So far the last option is winning, but I'd be much more content to use 
> it if the Emacs 26 are not going to need it.

I'm _really_ uneasy about putting this on the release branch.  sit-for
is notorious for subtle problems that take a lot of time to be
exposed.