bug#24004: 25.1.50; Animated images are no longer animated

[Lars Ingebrigtsen]

Test to reproduce:

`M-x eww RET
https://dropboxtechblog.files.wordpress.com/2016/07/lepton-4.gif RET'

That's an animated GIF, but Emacs does not animate it.  I don't know
when this started happening.


In GNU Emacs 25.1.50.2 (x86_64-unknown-linux-gnu, GTK+ Version 3.14.5)
 of 2016-07-14 built on stories
Repository revision: ff0ec6fd4d4779322aefa58df7329e47eb74bf72
Windowing system distributor 'The X.Org Foundation', version 11.0.11604000
System Description:     Debian GNU/Linux 8.5 (jessie)

Recent messages:
https://news.ycombinator.com/item?id=12094002 [2 times]
https://blogs.dropbox.com/tech/2016/07/lepton-image-compression-saving-22-losslessly-from-images-at-15mbs/
Contacting host: blogs.dropbox.com:443
Mark set
Contacting host: blogs.dropbox.com:443
Copied https://dropboxtechblog.files.wordpress.com/2016/07/lepton-4.gif
Contacting host: dropboxtechblog.files.wordpress.com:443
You can run the command ‘eww’ with G
Contacting host: dropboxtechblog.files.wordpress.com:443
Making completion list...

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

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Article

Minor modes in effect:
  diff-auto-refine-mode: t
  shell-dirtrack-mode: t
  global-whitespace-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t

Load-path shadows:
/home/larsi/src/cddb.el/expect hides /home/larsi/lisp/expect
/home/larsi/src/cddb.el/captitle hides /home/larsi/lisp/captitle
/home/larsi/src/clock.el/clock hides /home/larsi/lisp/clock
~/pgnus/contrib/vcard hides /home/larsi/lisp/vcard
/home/larsi/src/pvr.el/pvr hides /home/larsi/lisp/pvr
~/lisp/zenirc-2.112/src/zenirc-example hides /home/larsi/lisp/zenirc-example
~/pgnus/contrib/compface hides /home/larsi/src/emacs/trunk/lisp/image/compface

Features:
(shadow ecomplete emacsbug sendmail misearch multi-isearch flow-fill
shr-color color eww vc-git diff-mode cc-mode cc-fonts cc-guess cc-menus
cc-cmds cc-styles cc-align cc-engine cc-vars cc-defs copyright vc-cvs
shell pcomplete thingatpt grep compile comint ring map gnus-html
help-fns radix-tree url-queue url-cache mm-archive qp sort smiley
ansi-color gnus-cite gnus-async gnus-dup gnus-ml gmane spam-gmane dns
mm-url disp-table gnus-fun gnus-mdrtn gnus-topic pop3 nndoc nnmbox utf-7
nnml nnfolder network-stream starttls nnir spam-report spam spam-stat
gnus-uu yenc gnus-delay gnus-draft gnus-agent gnus-srvr gnus-score
score-mode nnvirtual nntp gnus-cache gnus-msg gnus-art mm-uu mml2015
mm-view mml-smime smime dig gnus-sum nndraft nnmh gnus-group gnus-undo
gnus-start gnus-cloud nnimap utf7 netrc nnoo parse-time gnus-spec
gnus-win nnmail gnus-int gnus-range mail-source message format-spec
rfc822 mml mml-sec epa epg mailabbrev gmm-utils mailheader gnus nnheader
gnus-util rmail rmail-loaddefs mail-utils whitespace movie mkv shr svg
imdb dom pvr debug debbugs-gnu easy-mmode derived debbugs soap-client
mm-decode mm-bodies mm-encode url-http tls gnutls url-auth mail-parse
rfc2231 rfc2047 rfc2045 mm-util ietf-drums mail-prsvr url-gw nsm puny
url url-proxy url-privacy url-expand url-methods url-history url-cookie
url-domsuf url-util mailcap warnings rng-xsd rng-dt rng-util xsd-regexp
xml ido flyspell ispell benchmark w3m browse-url doc-view subr-x dired
dired-loaddefs image-mode timezone w3m-hist w3m-fb w3m-ems wid-edit
w3m-ccl ccl w3m-favicon w3m-image w3m-proc w3m-util add-log mail-extr
jka-compr cl finder-inf package epg-config url-handlers url-parse
auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs
password-cache url-vars seq byte-opt gv bytecomp byte-compile cl-extra
help-mode easymenu cconv cl-loaddefs pcase cl-lib time-date mule-util
tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel term/x-win x-win 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 term/tty-colors 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 obarray 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:
((conses 16 1469381 84498)
 (symbols 48 173434 120)
 (miscs 40 212 1105)
 (strings 32 249596 7208)
 (string-bytes 1 16974210)
 (vectors 16 37752)
 (vector-slots 8 925166 54443)
 (floats 8 7028 4068)
 (intervals 56 199966 3707)
 (buffers 976 52)
 (heap 1024 189159 118430))

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no