[Bug-gnu-emacs] Display incorrect on very long lines (3000000 chars)

[John Abbott]

This bug report will be sent to the Free Software Foundation,
 not to your local site managers!!
Please write in English, because the Emacs maintainers do not have
translators to read other languages for them.

In GNU Emacs 20.5.1 (i386-redhat-linux-gnu, X toolkit)
 of Fri Feb  4 2000 on porky.devel.redhat.com
configured using `configure  --prefix=/usr --libexecdir=/usr/lib
--sharedstatedir=/var --with-gcc --with-pop --with-x-toolkit
i386-redhat-linux-gnu'

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

VERBAL DESCRIPTION:
emacs displays the wrong part of a file consisting of a very long line.
The problem manifests itself both with graphical emacs and emacs
running inside an xterm.  The problem is also apparent in files
consisting of several lines one of which is very long.  It would
seem that a line of three million characters exhibits the bug.

TO REPRODUCE THE PROBLEM:
[e.g. in a fresh emacs]
C-x C-b tmp
M-3000000 j

emacs does not display the end of the file as it should.

NOTE:
I suppose this is the same bug:
Trying to do "M-3000000 j" in the buffer *scratch* of a fresh graphical
emacs takes a long time; it is much faster in "emacs -nw".