bug#19288: 25.0.50; inferior-python-mode changes global value of comint-prompt-read-only

[mdl]

Inferior Python mode changes the global value of comint-prompt-read-only
to t, so that it affects all subsequently opened comint buffers.

Steps to reproduce:

emacs -Q
M-x run-python

...switch to another buffer (e.g., scratch)...

C-h v comint-prompt-read-only

comint-prompt-read-only is a variable defined in `comint.el'.
Its value is t
Original value was nil
...

The change was introduced in the following git commit:
6628be853e521167ca1dddbfc687cf27c486dad2



In GNU Emacs 25.0.50.2 (x86_64-unknown-linux-gnu, GTK+ Version 3.14.5)
 of 2014-12-02 on archthink
Repository revision: b1a765b3a8586cd53c21579982c8fbc0ce534336
Windowing system distributor `The X.Org Foundation', version 11.0.11602000
Configured using:
 `configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --mandir=/usr/share/man
 --pdfdir=/usr/share/doc/emacs/pdf --with-sound=alsa --without-gconf
 --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'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB

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

Major mode: Lisp Interaction

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

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

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message dired format-spec
rfc822 mml easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util help-fns mail-prsvr mail-utils time-date tooltip
eldoc 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 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 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 75106 6563)
 (symbols 48 18024 0)
 (miscs 40 38 149)
 (strings 32 11075 4921)
 (string-bytes 1 296844)
 (vectors 16 9348)
 (vector-slots 8 386527 15263)
 (floats 8 70 63)
 (intervals 56 196 1)
 (buffers 976 11)
 (heap 1024 45922 883))