bug#33363: 26.1; display problem with mode-line turned off on terminal

[Nick Helm <nick@tenpoint.co.nz>]

Running Emacs in a terminal and setting mode-line-format to nil can 
cause incorrect display of buffer contents.

emacs -Q -nw
M-: (setq mode-line-format nil)
C-x C-f lisp/org/org.el.gz ;for example
RET RET RET... DEL DEL DEL... ;add and delete white-space

Note the second-to-last row in the window, which formerly held the
mode-line, does not display the buffer contents correctly and any buffer
line that moves through the last row (when back-spacing) appears blank
further up the window.

I mainly observe this in emacs-lisp-mode and org-mode. The problem 
doesn't seem to occur when:

+ in fundamental-mode, c-mode or text-mode, or
+ visual-line-mode is active, or
+ the frame contains more than one window (v or h split), or
+ avoiding display of each line (e.g. C-u 10 RET C-u 10 DEL).


In GNU Emacs 26.1 (build 1, x86_64-apple-darwin14.5.0, NS appkit-1348.17 Version 10.10.5 (Build 14F2511))
 of 2018-05-31 built on builder10-10.porkrind.org
Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
 'configure --with-ns '--enable-locallisppath=/Library/Application
 Support/Emacs/${version}/site-lisp:/Library/Application
 Support/Emacs/site-lisp' --with-modules'

Configured features:
NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS MODULES THREADS

Important settings:
  value of $LANG: en_NZ.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  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
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny seq byte-opt gv
bytecomp byte-compile cconv cl-loaddefs cl-lib dired dired-loaddefs
format-spec rfc822 mml easymenu mml-sec password-cache epa derived epg
epg-config gnus-util rmail rmail-loaddefs mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils term/xterm xterm
time-date elec-pair tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel term/ns-win ns-win ucs-normalize mule-util
term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow isearch timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors 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 composite charscript charprop case-table epa-hook jka-cmpr-hook
help simple abbrev obarray 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 kqueue cocoa ns multi-tty make-network-process emacs)

Memory information:
((conses 16 208462 9630)
 (symbols 48 20166 1)
 (miscs 40 34 154)
 (strings 32 29167 1089)
 (string-bytes 1 765466)
 (vectors 16 32985)
 (vector-slots 8 673123 13352)
 (floats 8 52 452)
 (intervals 56 197 0)
 (buffers 992 12))