bug#22917: 24.5; comint-kill-region doesn't work when both cua-mode and comint-prompt-read-only enabled

[a . c . kalker]

Steps to reproduce:

1. Create file 'repro.el' with contents:

;; Test deleting region with read-only prompts while cua-mode is active
(setq comint-prompt-read-only t)
(cua-mode 1)
;; Copied verbatim from 'comint-prompt-read-only' docstring
(add-hook 'comint-mode-hook
          (lambda ()
            (define-key comint-mode-map [remap kill-region] 'comint-kill-region)
            (define-key comint-mode-map [remap kill-whole-line]
              'comint-kill-whole-line)))

2. Run Emacs and start a shell
$ emacs -Q -l repro.el
M-x shell RET

3. In the shell, execute a command, then select a region comprising the
command's output and one or more prompts, like the following (region
shown delimited by '[' and ']'):
[miki@miki-desktop ~]$ date
Sat Mar  5 15:49:31 CET 2016
[miki@miki-desktop ~]$ [uname -a
Linux miki-desktop 4.4.3-1-ARCH #1 SMP PREEMPT Fri Feb 26 15:09:29 CET 2016 
x86_64 GNU/Linux
[miki@miki-desktop ~]$ ]

4. Hit C-x or <delete> (only when cua-mode is active) or <S-delete> or C-w

5. Retry steps 3 and 4 after disabling cua-mode with M-x cua-mode RET

Expected results:
All these keystrokes (where applicable) should delete the region,
including any interspersed prompts.

Actual results:
With cua-mode enabled:
4. C-x produces the error: "Text is read-only: #<buffer *shell*>" and
nothing is deleted.
   <delete> produces the error: "Text is read-only" and nothing is
   deleted.
   <S-delete> produces the error: "Text is read-only: #<buffer *shell*>" and
nothing is deleted.
   C-w  produces the error: "Text is read-only: #<buffer *shell*>" and
nothing is deleted.
With cua-mode disabled:
4. <S-delete> deletes the region, without error.
   C-w deletes the region, without error.



In GNU Emacs 24.5.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.16.6)
 of 2015-09-10 on foutrelis
Windowing system distributor `The X.Org Foundation', version 11.0.11801000
Configured using:
 `configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --with-x-toolkit=gtk3 --with-xft
 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong
 --param=ssp-buffer-size=4' CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro'

Important settings:
  value of $LC_MESSAGES: en_US.utf8
  value of $LANG: en_US.utf8
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  yas-global-mode: t
  delete-selection-mode: t
  winner-mode: t
  show-paren-mode: t
  icomplete-mode: t
  global-whitespace-mode: t
  cua-mode: t
  multi-web-global-mode: t
  global-flycheck-mode: t
  global-company-mode: t
  override-global-mode: t
  msb-mode: t
  tooltip-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t
  view-mode: t

Recent messages:
[yas] Loading snippet files from 
/home/miki/.emacs.d/elpa/yasnippet-20160226.1359/snippets/emacs-lisp-mode
[yas] Loading for `prog-mode', just-in-time: (lambda nil (yas--load-directory-1 
(quote /home/miki/.emacs.d/elpa/yasnippet-20160226.1359/snippets/prog-mode) 
(quote prog-mode)))!
[yas] Loading snippet files from 
/home/miki/.emacs.d/elpa/yasnippet-20160226.1359/snippets/prog-mode
Loading 
/home/miki/.emacs.d/elpa/yasnippet-20160226.1359/snippets/prog-mode/.yas-setup...done
For information about GNU Emacs and the GNU system, type C-h C-a.
View mode: type C-h for help, h for commands, q to quit.
Making completion list...
Contacting host: debbugs.gnu.org:80 [3 times]
Opening nndoc server on /tmp/gnus-temp-group-11073W9u-ephemeral...done
Beginning of buffer
gnus-summary-next-unread-article: No buffer named *Group* [2 times]

Load-path shadows:
/home/miki/.emacs.d/elpa/helm-20160304.713/helm-multi-match hides 
/home/miki/.emacs.d/elpa/helm-core-20160303.1321/helm-multi-match
/usr/share/emacs/site-lisp/SuperCollider/tree-widget hides 
/usr/share/emacs/24.5/lisp/tree-widget

Features:
(shadow emacsbug sendmail parse-time sort smiley ansi-color gnus-cite
mail-extr qp gnus-async gnus-bcklg gnus-agent gnus-srvr gnus-score
score-mode nnvirtual nntp gnus-ml gnus-msg disp-table nndoc gnus-cache
url-handlers gnus-dup gnus-art mm-uu mml2015 mm-view mml-smime smime dig
gnus-sum nnoo gnus-group gnus-undo nnmail mail-source gnus-start
gnus-spec gnus-int gnus-range gnus-win gnus gnus-ems nnheader wid-edit
async mm-archive message idna format-spec rfc822 mml mml-sec mailabbrev
gmm-utils mailheader mail-utils network-stream starttls url-cache
debbugs-gnu add-log debbugs soap-client warnings xml mule-util view
eldoc hideshow adjust-parens elisp-slime-nav hl-sexp .emacs server
yasnippet cl imenu company-oddmuse company-keywords company-etags etags
company-gtags company-dabbrev-code company-dabbrev company-files
company-capf company-cmake company-xcode company-clang company-semantic
company-eclim company-template company-css company-nxml company-bbdb
company-irony irony-completion irony-snippet irony company-tern s
ucs-normalize dash-functional finder-inf tern url-http tls url-auth
url-gw url url-proxy url-privacy url-expand url-methods url-history
url-cookie url-domsuf url-util mailcap wheatgrass-theme delsel winner
ring paren icomplete whitespace cua-base cus-start cus-load shackle
multi-web-mode flycheck find-func help-mode rx subr-x seq dash company
cl-macs gv pcase quelpa-use-package advice quelpa package-build
mm-decode mm-bodies mm-encode mail-parse rfc2231 rfc2047 rfc2045
ietf-drums json lisp-mnt use-package diminish bind-key easy-mmode
slime-autoloads info easymenu package epg-config ffap thingatpt
url-parse auth-source eieio byte-opt bytecomp byte-compile cl-extra
cconv eieio-core gnus-util mm-util help-fns mail-prsvr password-cache
url-vars edmacro kmacro cl-loaddefs cl-lib windmove msb time-date
tooltip electric uniquify ediff-hook vc-hooks lisp-float-type mwheel
x-win x-dnd tool-bar dnd fontset image regexp-opt fringe tabulated-list
newcomment lisp-mode prog-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 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 make-network-process
dbusbind gfilenotify dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty emacs)

Memory information:
((conses 16 419412 21695)
 (symbols 48 39756 1)
 (miscs 40 290 448)
 (strings 32 82726 13188)
 (string-bytes 1 2585001)
 (vectors 16 54491)
 (vector-slots 8 946354 13153)
 (floats 8 621 453)
 (intervals 56 368 79)
 (buffers 960 23)
 (heap 1024 41393 1828))