bug#11338: 24.1.50; read-buffer-completion-ignore-case fails on one-character names

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Tue, 08 Dec 2020 14:57:34 +0100
> Cc: 11338@debbugs.gnu.org
> 
> I've never used that variable before, and the behaviour was unexpected
> to me, but I don't know what people who do use it expect.  It's pretty
> odd, though -- the variable is about completion, but Emacs now seems to
> interpret it as "Emacs should ignore all case differences in buffer
> names (interactively)", which is something slightly different.

RET in the minibuffer invokes completion, doesn't it?