bug#15513: 24.2; isearch should clear selection in transient-mark-mode

[Yuri Khan <yuri.v.khan@gmail.com>]

This bug report will be sent to the Bug-GNU-Emacs mailing list
and the GNU bug tracker at debbugs.gnu.org.  Please check that
the From: line contains a valid email address.  After a delay of up
to one day, you should receive an acknowledgement at that address.

Please write in English if possible, as the Emacs maintainers
usually do not have translators for other languages.

Please describe exactly what actions triggered the bug, and
the precise symptoms of the bug.  If you can, give a recipe
starting from `emacs -Q':

1. Start `emacs -Q'. It opens Emacs with the default text in *scratch*
buffer:
;; This buffer is for notes you don't want[...]
1a. cua-mode is off, transient-mark-mode is on.
2. Move point before This.
3. Select the word This by pressing Ctrl+Shift+Right arrow.
4. Invoke isearch by pressing Ctrl+S.
5. Enter `notes' as the search string.

Observed behavior:
* Selection is extended to include the word that was found by isearch.

Expected behavior:
* Since isearch is a point movement command and such commands deactivate
the selection in transient-mark-mode, I expect selection to be
deactivated.
* If I press Ctrl+Space before searching, this indicates an explicit
request for persistent selection. In this case, the current behavior of
isearch is correct.
* Additionally, it might be nice if pressing Ctrl+Shift+S behaved
similarly to Shift+arrow keys, unconditionally activating the selection
and extending/shrinking it to include the match.


In GNU Emacs 24.2.1 (x86_64-pc-linux-gnu, GTK+ Version 3.6.4)
 of 2013-04-09 on allspice, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.11303000
Configured using:
 `configure '--build' 'x86_64-linux-gnu' '--build' 'x86_64-linux-gnu'
 '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib'
 '--localstatedir=/var/lib' '--infodir=/usr/share/info'
 '--mandir=/usr/share/man' '--with-pop=yes'
 '--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.2/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.2/site-lisp:/usr/share/emacs/site-lisp'
 '--with-crt-dir=/usr/lib/x86_64-linux-gnu' '--with-x=yes'
 '--with-x-toolkit=gtk3' '--with-toolkit-scroll-bars'
 'build_alias=x86_64-linux-gnu' 'CFLAGS=-g -O2 -fstack-protector
 --param=ssp-buffer-size=4 -Wformat -Werror=format-security -Wall'
 'LDFLAGS=-Wl,-Bsymbolic-functions -Wl,-z,relro'
 'CPPFLAGS=-D_FORTIFY_SOURCE=2''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: en_RU.UTF-8
  value of $LC_NUMERIC: en_RU.UTF-8
  value of $LC_TIME: en_RU.UTF-8
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-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 input:
M-x e m a <backspace> <backspace> <backspace> r e p
o s <backspace> r t <tab> <return>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Load-path shadows:
/usr/share/emacs/24.2/site-lisp/debian-startup hides
/usr/share/emacs/site-lisp/debian-startup
/usr/share/emacs/24.2/site-lisp/dictionaries-common/flyspell hides
/usr/share/emacs/24.2/lisp/textmodes/flyspell
/usr/share/emacs/24.2/site-lisp/dictionaries-common/ispell hides
/usr/share/emacs/24.2/lisp/textmodes/ispell

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail regexp-opt rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils time-date tooltip ediff-hook
vc-hooks lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image
fringe lisp-mode register page menu-bar rfn-eshadow timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core frame cham
georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese hebrew greek romanian slovak czech european ethiopic
indian cyrillic chinese case-table epa-hook jka-cmpr-hook help simple
abbrev minibuffer loaddefs button faces cus-face files text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process dbusbind
dynamic-setting system-font-setting font-render-setting move-toolbar gtk
x-toolkit x multi-tty emacs)