bug#24364: 25.1; C-x C-x in rectangle-mark-mode leaves corner out

[Marie-Christine Jones]

When point is at the end of the (*scratch*-) buffer and
rectangle-mark-mode is activated, C-x C-x cycles through all corners but
the bottom left one, in this order (starting in the top right corner):
bottom right, top left, bottom right, top right.  I think it should go
to the bottom left corner as well.

Starting from 'emacs -Q':

 C-x SPC [rectangle-mark-mode]
 C-p [rectangle-previous-line]
 C-p [rectangle-previous-line]
 C-f [rectangle-forward-char]
 C-f [rectangle-forward-char]
 C-x C-x [rectangle-exchange-point-and-mark]
 C-x C-x [rectangle-exchange-point-and-mark]
 C-x C-x [rectangle-exchange-point-and-mark]
 C-x C-x [rectangle-exchange-point-and-mark]
 C-h l [view-lossage]



In GNU Emacs 25.1.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.14.5)
 of 2016-08-22 built on slartibartfast
Windowing system distributor 'The X.Org Foundation', version 11.0.11604000
System Description:     Debian GNU/Linux 8.5 (jessie)

Configured features:
XPM JPEG TIFF GIF PNG SOUND GPM DBUS GSETTINGS NOTIFY LIBXML2 FREETYPE
XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11

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

Major mode: Lisp Interaction

Minor modes in effect:
  rectangle-mark-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:
For information about GNU Emacs and the GNU system, type C-h C-a.
Mark set (rectangle mode)
Type C-x 1 to delete the help window.

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 mail-prsvr mail-utils
help-mode easymenu cl-loaddefs pcase cl-lib rect 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 88335 8634)
 (symbols 48 20096 0)
 (miscs 40 122 146)
 (strings 32 15021 4385)
 (string-bytes 1 426328)
 (vectors 16 12084)
 (vector-slots 8 441102 4380)
 (floats 8 169 31)
 (intervals 56 193 0)
 (buffers 976 18)
 (heap 1024 50002 4363))