bug#37556: gpg "-unknown" version string

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Mon, 30 Sep 2019 07:34:45 +0200
> Cc: 37556@debbugs.gnu.org
> 
> Juanma Barranquero <lekktu@gmail.com> writes:
> 
> > I think it makes more sense just adding "-unknown" to the formats
> > recognized by default with version-regexp-alist.
> 
> Hm...  I guess that would make sense, but might there be other
> ramifications?  All callers to version-to-list may get other data back
> than they are used to?

"-unknown" is unusual in version strings, IME.  If this is somehow
related to gpg, maybe we should chop that before we invoke the
version-comparison functions, in gpg-related Lisp files only?