bug#24291: 25.1; display-time-world seems to ignore zoneinfo-style-world-list when display-time-mode is t

[nljlistbox2@gmail.com (N. Jackson)]

The command display-time-world seems to be ignoring the
zoneinfo-style-world-list variable; instead, the time for the default
list of cities is displayed.

Setting zoneinfo-style-world-list in `emacs -Q' works as expected, so I
bisected my init file and it seems that the problem is "caused" by
setting display-time-mode to show the clock in the mode line.

This recipe shows the problem from `emacs -Q'

0. emacs -Q

1. Enter the following elisp in *scratch*:

  (custom-set-variables
   '(display-time-mode t)
   '(zoneinfo-style-world-list
     (quote
      (("Etc/UTC" "Universal Time")
       ("AST4ADT" "Atlantic Time")
       ("EST5EDT" "Eastern Time")
       ("Europe/London" "London")
       ("Asia/Tokyo" "Tokyo")))))

2. `C-x C-e' (eval-last-sexp) to run it

3. `M-x display-time-world'

Observed result:

  Seattle   Tuesday 23 August 04:22 PDT
  New York  Tuesday 23 August 07:22 EDT
  London    Tuesday 23 August 12:22 BST
  Paris     Tuesday 23 August 13:22 CEST
  Bangalore Tuesday 23 August 16:52 IST
  Tokyo     Tuesday 23 August 20:22 JST

Expected result:

  Universal Time Tuesday 23 August 11:24 UTC
  Atlantic Time  Tuesday 23 August 08:24 ADT
  Eastern Time   Tuesday 23 August 07:24 EDT
  London         Tuesday 23 August 12:24 BST
  Tokyo          Tuesday 23 August 20:24 JST


If the recipe above is modified to remove the line that sets
display-time-mode, the output is as expected.

I'm more than slightly confused by what I'm observing here. I don't
believe it was more than a couple of months ago that I set z-s-w-l for
the first time. It worked perfectly then even though I always have d-t-m
on (because the mode line clock is the one I use to know what time it is
during the day). But now I'm seeing the reported problem in versions of
the Emacs 25 pre-release going back for months, and indeed, in Emacs
24.5.


In GNU Emacs 25.1.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.18.9)
 of 2016-07-24 built on moondust
Windowing system distributor 'Fedora Project', version 11.0.11803000
System Description:	Fedora release 23 (Twenty Three)

Configured using:
 'configure --prefix=/home/nlj/local/ --enable-checking=yes,glyphs
 --enable-check-lisp-object-type 'CFLAGS=-O2 -g3 -gdwarf-4''

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GCONF GSETTINGS NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11

Important settings:
  value of $LC_MONETARY: en_DK.utf8
  value of $LC_NUMERIC: en_DK.utf8
  value of $LC_TIME: en_DK.utf8
  value of $LANG: en_CA.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix


Features:
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gnus-srvr gnus-score score-mode nnvirtual gnus-msg nntp gnus-cache
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ansi-color ring ob-core ob-eval org-compat org-macs org-loaddefs
format-spec find-func bbdb-anniv diary-lib diary-loaddefs cal-menu
calendar cal-loaddefs bbdb-com crm mailabbrev bbdb bbdb-site timezone
bbdb-loaddefs finder-inf tex-site info package epg-config seq byte-opt
gv bytecomp byte-compile cl-extra help-mode cconv edmacro kmacro recentf
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term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list newcomment elisp-mode lisp-mode prog-mode register page
menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock font-lock
syntax facemenu font-core frame cl-generic cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms
cp51932 hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese charscript case-table epa-hook jka-cmpr-hook help
simple abbrev minibuffer cl-preloaded nadvice loaddefs button faces
cus-face macroexp files text-properties overlay sha1 md5 base64 format
env code-pages mule custom widget hashtable-print-readable backquote
dbusbind inotify dynamic-setting system-font-setting font-render-setting
move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
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