bug#31415: 27.0.50; Strange behavior on Command-$ in MacOS

[John Mastro <john.b.mastro@gmail.com>]

By default, the "command" key in MacOS is bound to "super". If I type
s-$, Emacs seems to wait for input that it never receives. Anything I
type afterward appears to be ignored, except `ESC ESC ESC', which gets
Emacs out of this state. However, even hitting `C-g' repeatedly does
not.

The issue seems to be related to the command key rather than to "super"
or to the command bound to the key. In my configuration, I map command
to meta, and the same problem happens when I use M-$ to `ispell-word'.

Using `M-$' with command as meta worked until relatively recently. It
would be great if it could be brought back or made to fail more
explicitly.

Please let me know if I can provide any additional information.

Thanks,

John

In GNU Emacs 27.0.50 (build 7, x86_64-apple-darwin17.5.0, NS
appkit-1561.40 Version 10.13.4 (Build 17E202))
 of 2018-05-10 built on nebula.local
Repository revision: eabb6f6c3ee75dac1a7510e80bdd3c2fcfbbbcb5
Windowing system distributor 'Apple', version 10.3.1561
System Description:  Mac OS X 10.13.4

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
M-g C-g is undefined
Type C-x 1 to delete the help window, C-M-v to scroll help.


Configured using:
 'configure --with-xml2 --with-zlib --with-gnutls --with-imagemagick
 --without-pop --without-compress-install --with-ns 'LDFLAGS=-L
 /usr/local/opt/libxml2/lib' 'CFLAGS=-pipe -march=nocona -O2 -g3 -I
 /usr/local/opt/libxml2/include'
 PKG_CONFIG_PATH=/usr/local/opt/libxml2/lib/pkgconfig'

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

Important settings:
  value of $LANG: en_US.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 dired dired-loaddefs format-spec rfc822 mml
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 cl-extra ispell help-fns radix-tree
help-mode easymenu cl-loaddefs cl-lib 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 207650 11053)
 (symbols 48 20141 1)
 (miscs 40 46 233)
 (strings 32 30424 1816)
 (string-bytes 1 807306)
 (vectors 16 35684)
 (vector-slots 8 720328 18424)
 (floats 8 49 67)
 (intervals 56 260 0)
 (buffers 992 12))