Eamcs 22.1 comint-scroll-show-maximum-output bug

[William Paul Vrotney <vrotney@earthlink.net>]

BUG DESCRIPTION:

First noticed in Emacs 22.1.  The comint variable

    comint-scroll-show-maximum-output 

does not work as documented when set to nil.  For example when setting this
variable to nil when using M-x shell the Emacs 22.1 manual says

        41.7 Shell Mode Options

           If `comint-scroll-show-maximum-output' is non-`nil', then arrival
        of output when point is at the end tries to scroll the last line of
        text to the bottom line of the window, showing as much useful text
        as possible.  (This mimics the scrolling behavior of most
        terminals.)  The default is `t'.


BUG REPLICATION:

    Emacs source: from http://ftp.gnu.org emacs-22.1.tar.gz
    Build: Simply: configure; make; make install;
    Emacs M-x version: Its value is "22.1.1"
    Operating System: Fedora core 3
    Emacs Invocation: emacs -q

    Then if you then do the following

        M-x set-variable comint-scroll-show-maximum-output nil
        M-x shell

    then once the shell buffer becomes full every output still scrolls the
    last line of text to the bottom as it does when
    comint-scroll-show-maximum-output is set to t.

    I've tried setting this variable in all possible ways: before/after
    running M-x shell and using 'setq' in ~/.emacs, 'M-x set-variable' and
    'M-x customize.  But with all the same results as explained above.


OTHER INFORMATION:  The M-x shell defaults to running the bash shell.

ADDITIONAL RELATED BUG:

    When I run the command M-x shell with comint-scroll-show-maximum-output
    set to nil the shell buffer window does not show the first line of bash
    shell output.  In my case it the first line of my two line prompt.  If I
    type M-x recenter then the first line of bash shell output comes into
    view in the buffer window.

PATCH: 

    If I use Emacs 22.1 but load in my ~/.emacs the comint.elc from Emacs
    21.3 then all works fine as it did for Emacs 23.1 and earlier.