bug#3435: 23.0.91; Two-column mode don't split columns correctly

In two-column mode there is "2C-split" (C-x 6 s) command which is
supposed to detect the split column and then split window vertically
etc. The column detection does not work correctly in my Emacs 23.0.91.1.

Example file:

    foo  123
    bar  456

Put the point before the "1" and try the 2C-split command (C-x 6 s). The
left buffer/window contains this:

    foo
    bar  456

And the right buffer/window contains this:

    123

Only the first line is actually split.

There is another minor bug: "2C-dissociate" (C-x 6 d) command does not
update the modeline. It looks like 2C mode is still turned on even
though it isn't. Then "recenter-top-bottom" (C-l) updates the modeline.



In GNU Emacs 23.0.91.1 (i486-pc-linux-gnu, GTK+ Version 2.12.11)
 of 2009-03-21 on elegiac, modified by Debian
 (emacs-snapshot package, version 1:20090320-1~lenny1)
Windowing system distributor `The X.Org Foundation', version 11.0.10402000
configured using `configure  '--build' 'i486-linux-gnu' '--host' 'i486-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' '--localstatedir=/var' '--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes' '--enable-locallisppath=/etc/emacs-snapshot:/etc/emacs:/usr/local/share/emacs/23.0.91/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.0.91/site-lisp:/usr/share/emacs/site-lisp' '--with-x=yes' '--with-x-toolkit=gtk' 'build_alias=i486-linux-gnu' 'host_alias=i486-linux-gnu' 'CFLAGS=-DDEBIAN -DSITELOAD_PURESIZE_EXTRA=5000 -g -O2' 'LDFLAGS=-g -Wl,--as-needed' 'CPPFLAGS=''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: en_US.UTF-8
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: fi_FI.UTF-8
  value of $XMODIFIERS: @im=none
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t