bug#21110: 25.0.50; Images viewed with Image[Imagemagick] mode are garbled

[Robert Marshall <robert@capuchin.co.uk>]

I ran emacs -Q imagefile.png
and on viewing the buffer it consists of garbage which appears to be
assembled from parts of the X display (if required I can produce a screenshot)

Same problem is apparent with jpg and gifs. If I use the display command
from the command line (or from an emacs dired buffer) the images are
correctly displayed

In GNU Emacs 25.0.50.3 (i686-pc-linux-gnu, GTK+ Version 3.14.13, cairo version 1.14.2)
 of 2015-07-22 on poulenc
Repository revision: fed091f7c2513631d8c0570f444be9486d7563d1
Windowing system distributor `The X.Org Foundation', version 11.0.11701000
System Description:	Ubuntu 15.04

Configured using:
 `configure --with-cairo'

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

Important settings:
  value of $LANG: en_GB.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Image[imagemagick]

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-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
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Type C-c C-c to view the image as text. [2 times]
scroll-down-command: Beginning of buffer
Type C-c C-c to view the image as text.
Type C-x 1 to delete the help window, C-M-v to scroll help.
Mark saved where search started
"robert@capuchin.co.uk"
Mark saved where search started
"faure" [2 times]
Quit [2 times]

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils misearch multi-isearch cl-extra seq help-fns
help-mode cl-loaddefs pcase cl-lib image-mode easymenu dired time-date
mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel 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 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 gfilenotify dynamic-setting
system-font-setting font-render-setting cairo move-toolbar gtk x-toolkit
x multi-tty make-network-process emacs)

Memory information:
((conses 8 87967 9743)
 (symbols 24 19083 0)
 (miscs 20 134 285)
 (strings 16 15280 26489)
 (string-bytes 1 414619)
 (vectors 8 11228)
 (vector-slots 4 462309 5618)
 (floats 8 138 174)
 (intervals 28 957 14)
 (buffers 520 16)
 (heap 1024 41613 748))