bug#14508: scroll-conservatively==1 not honored for fast line by line navigation up

[Barry OReilly]

Let /tmp/scroll-conservatively-1.el have this content:

  (setq scroll-conservatively 1)
  (add-hook 'term-setup-hook (lambda () (goto-char (point-max))))

And /tmp/foo.cpp as attached.

Also set the keyboard repitition rate somewhat high.

Start Emacs by: emacs -Q /tmp/foo.cpp --load /tmp/scroll-conservatively-1.el

Hold arrow up key, recentering occurs while scrolling up.

Note: Script goes to EOB because I only witness this for scroll ups, not scroll downs.

I witness this regularly when navigating C++ source code.

----

In GNU Emacs 24.3.50.6 (x86_64-unknown-linux-gnu, GTK+ Version 2.10.4)
 of 2013-05-23 on redacted
Windowing system distributor `The X.Org Foundation', version 11.0.70101000
System Description:    Red Hat Enterprise Linux Client release 5.4 (Tikanga)

Configured using:
 `configure --prefix=/redacted/user/boreilly/sw/emacs-install-trunk
 --with-gif=no'

Important settings:
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=none
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: C++/l

Minor modes in effect:
  tooltip-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
  abbrev-mode: t

Recent input:
M-x r e p o r t - e m a c <tab> <return>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
foo.cpp has auto save data; consider M-x recover-this-file
Loading cc-langs...done

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message cl-macs gv format-spec
rfc822 mml mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils cc-langs cl nadvice cl-lib cc-mode
cc-fonts easymenu cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine
cc-vars cc-defs time-date tooltip 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 register page menu-bar rfn-eshadow
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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 dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty emacs)

foo.cpp
Description: Text Data