bug#32731: 26.1.50; Ibuffer filter by mode: Handle >1 mode names

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: Tino Calancha <tino.calancha@gmail.com>,  32731@debbugs.gnu.org,  
> npostavs@gmail.com,  rms@gnu.org
> Date: Tue, 25 Sep 2018 10:14:11 +0200
> 
> > I usually just rewrite the text to be in plural, like "the users"
> > instead of "the user".  Then "they" is correct English.
> 
> Point of order: singular they has been correct English for the last
> 700 years. Some people donʼt like it, but that doesnʼt make it wrong.

"Some people" seem to include Richard, who said a few messages ago:

> Using "they" for a singular antecedent is confusing, and I always find
> it jarring.  I won't make a rule against, but I make a point of never
> using that construction.

Thus my preference to rewrite in plural.