bug#19889:

[Eli Zaretskii]

> From: Glenn Morris <rgm@gnu.org>
> Date: Fri, 06 May 2016 16:22:53 -0400
> Cc: 19889@debbugs.gnu.org
> 
> PS Manually setting the font family to "Nimbus Mono L" works.
> This is what fc-match returns for me:
> 
>   fc-match courier
>   n022003l.pfb: "Nimbus Mono L" "Regular"
> 
> Yet for "font family: courier", Emacs selects x:-adobe-courier-medium,
> for some reason.

Both belong to the Courier family, right?  So which one is found first
is entirely implementation-dependent.

When we ask for a family, we are saying that we will accept _any_
member of that family.  If we are unwilling to accept some of its
members, we should request a specific font (or maybe specify more than
just a family, but I'm not aware of any such additional specs;
foundry, perhaps?).