bug#39390: 28.0.50; prettify-symbols-mode confuses display when start/end faces are different

[Eli Zaretskii]

> Date: Sun, 16 Feb 2020 21:29:50 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 39390@debbugs.gnu.org
> 
> One.  Copy/paste reveals that there are two in the buffer, but they
> display as one.

Actually, I take that back: what's in the buffer is "abc", and it
displays as a single @.  I simply copy/pasted from your message and
forgot to delete one @.  Sorry for the confusion.