bug#9794: 24.0.90; `format-time-string' no good for %Z

[Eli Zaretskii]

> From: Andreas Schwab <schwab@linux-m68k.org>
> Cc: Paul Eggert <eggert@cs.ucla.edu>,  9794@debbugs.gnu.org
> Date: Thu, 20 Oct 2011 11:46:06 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Fixed how?  Given some arbitrary string, how can Lisp code check
> > whether it is or isn't compliant?
> 
> By using %z.

That's _after_ you discover that the string returned by %Z is
non-compliant.  My question was ho to discover that, sorry for being
unclear.