bug#25055: 25.1.50; completion buffer changes window size

[Tyler Smith]

To reproduce:

1. start emacs -Q
2. M-x shell
3. ls ./<tab><tab>
4. A temporary buffer pops up with all possible completions.
   - if your home directory is big enough, this buffer will take up a
   large portion of the frame
5. press <space>
6. The completions are dismissed, but the frame remains in its new
configuration, with 90% of the space taken up by the window where the
completions had been listed (this window has now returned to the
shell-mode buffer).

What I would expect to happen instead is that when the completions are
dismissed, the window configuration returns to the state it was in
before pressing tab: that is, the top half is the scratch buffer, the
bottom half is the shell-mode buffer.


Thanks,

Tyler


In GNU Emacs 25.1.50.3 (x86_64-pc-linux-gnu, GTK+ Version 3.22.2)
 of 2016-11-20 built on tardis
Repository revision: 3138598dd87d3578cee220436d1c7857a9aca896
Windowing system distributor 'The X.Org Foundation', version
11.0.11804000
System Description:     Debian GNU/Linux testing (stretch)

Configured using:
 'configure --with-x-toolkit=gtk'

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_CA.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  shell-dirtrack-mode: t
  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:
Complete, but not unique
Making completion list...
Complete, but not unique [2 times]
Making completion list...
Complete, but not unique [2 times]
Making completion list...
Complete, but not unique [2 times]
GNU Emacs 25.1.50.3 (x86_64-pc-linux-gnu, GTK+ Version 3.22.2) of
2016-11-20
You can run the command ‘emacs-version’ with M-x em-v RET
GNU Emacs 25.1.50.3 (x86_64-pc-linux-gnu, GTK+ Version 3.22.2) of
2016-11-20

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message dired format-spec rfc822 mml
mml-sec password-cache epg epg-config gnus-util mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums mm-util help-fns help-mode easymenu
cl-loaddefs pcase cl-lib mail-prsvr mail-utils shell pcomplete comint
ansi-color ring 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 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 92318 6553)
 (symbols 48 20433 0)
 (miscs 40 68 146)
 (strings 32 16444 4822)
 (string-bytes 1 471026)
 (vectors 16 12572)
 (vector-slots 8 441992 5013)
 (floats 8 168 188)
 (intervals 56 664 334)
 (buffers 976 22))