bug#16878: 24.3.50; gif animation continues even after killing buffer

[Ivan Kanis]

1) emacs -Q
2) M-x eww https://github.com/ShingoFukuyama/emacs-swoop RET
3) Wait for the emacs screenshot to load.
4) C-x k RET

I expect emacs to stop processing the animated gif. Instead emacs is
pegged at 100% cpu. Doing a C-z in the debugger shows it is still
processing the gif. This renders emacs unusable and I have to restart
it.

I think the slowness of rendering animated gif is a bug too. I know I
run on a under powered PC but Firefox has no problem rendering animated
gif.

^Z
Program received signal SIGTSTP, Stopped (user).
0xabeb40e3 in ?? ()
   from /usr/lib/i386-linux-gnu/ImageMagick-6.7.7/modules-Q16/coders/gif.so
(gdb) bt
#0  0xabeb40e3 in ?? ()
   from /usr/lib/i386-linux-gnu/ImageMagick-6.7.7/modules-Q16/coders/gif.so
#1  0xb706722a in ReadImage () from /usr/lib/i386-linux-gnu/libMagickCore.so.5
#2  0xb702ca32 in BlobToImage ()
   from /usr/lib/i386-linux-gnu/libMagickCore.so.5
#3  0xb7341973 in MagickReadImageBlob ()
   from /usr/lib/i386-linux-gnu/libMagickWand.so.5
#4  0x0825f74e in imagemagick_load_image (f=0x885a3e8, img=0x8d6d600, 
    contents=0x9a8ff24 "GIF89a[\003U\002w", size=7729394, filename=0x0)
    at image.c:8193
#5  0x08260373 in imagemagick_load (f=0x885a3e8, img=0x8d6d600) at image.c:8515
#6  0x0825658f in lookup_image (f=0x885a3e8, spec=143734606) at image.c:1694
#7  0x082552f5 in Fimage_metadata (spec=143734606, frame=140327874)
    at image.c:945
#8  0x081db61f in Ffuncall (nargs=2, args=0xbfffd7c4) at eval.c:2816


In GNU Emacs 24.3.50.1 (i686-pc-linux-gnu, GTK+ Version 2.24.20)
 of 2014-02-08 on tao.kanis.fr
Repository revision: 116348 
michael.albinus@gmx.de-20140208133515-mgy8agwqq4nc6bfb
Windowing system distributor `The X.Org Foundation', version 11.0.11403000
System Description:     Ubuntu 13.10

Configured using:
 `configure --prefix=/home/ivan/emacs-bzr --without-compress-install
 'CFLAGS=-g'

Important settings:
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  blink-cursor-mode: t
  auto-composition-mode: t
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