bug#49186: ansi-term switch to char mode immediately executes string at prompt

[simon254]

One can switch from char-mode to line-mode via C-c C-j to copy text /
enter text etc. Unfortunately, when changing back to char-mode, it always sends 
a return to the shell.
This was not the case in emacs 26

For example, C-c C-j, then typing ls and then C-c C-k -> ls is
executed. However, If I type ls and then C-c C-j followed by C-c C-k, it does 
not execute ls

Bug affects emacs version 27 and 28

In GNU Emacs 28.0.50 (build 1, x86_64-apple-darwin20.5.0, NS appkit-2022.50 
Version 11.4 (Build 20F71))
 of 2021-06-06 built on two.local
Windowing system distributor 'Apple', version 10.3.2022
System Description:  macOS 11.4

Configured using:
 'configure --disable-dependency-tracking --disable-silent-rules
 --enable-locallisppath=/usr/local/share/emacs/site-lisp
 --infodir=/usr/local/Cellar/emacs-plus@28/28.0.50/share/info/emacs
 --prefix=/usr/local/Cellar/emacs-plus@28/28.0.50 --with-xml2
 --with-gnutls --with-native-compilation --without-dbus
 --with-imagemagick --with-modules --with-rsvg --with-ns
 --disable-ns-self-contained 'CFLAGS=-I/usr/local/opt/gcc/include
 -I/usr/local/opt/libgccjit/include -I/usr/local/opt/gmp/include
 -I/usr/local/opt/jpeg/include' 'LDFLAGS=-L/usr/local/lib/gcc/11
 -I/usr/local/opt/gcc/include -I/usr/local/opt/libgccjit/include
 -I/usr/local/opt/gmp/include -I/usr/local/opt/jpeg/include''

Configured features:
ACL GIF GLIB GMP GNUTLS IMAGEMAGICK JPEG JSON LCMS2 LIBXML2 MODULES
NATIVE_COMP NOTIFY KQUEUE NS PDUMPER PNG RSVG THREADS TIFF
TOOLKIT_SCROLL_BARS XIM ZLIB

Important settings:
  value of $LANG: en_GB.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
  blink-cursor-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 dired dired-loaddefs
rfc822 mml mml-sec epa derived epg epg-config gnus-util rmail
rmail-loaddefs auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs password-cache json map text-property-search time-date
subr-x seq byte-opt gv bytecomp byte-compile cconv mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader cl-loaddefs
cl-lib sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils
iso-transl 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 tab-bar menu-bar rfn-eshadow isearch easymenu
timer select scroll-bar mouse jit-lock font-lock syntax font-core
term/tty-colors frame minibuffer 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 cl-preloaded nadvice button
loaddefs faces cus-face macroexp files window text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote threads kqueue cocoa ns lcms2
multi-tty make-network-process native-compile emacs)

Memory information:
((conses 16 68746 8679)
 (symbols 48 6527 0)
 (strings 32 18707 1877)
 (string-bytes 1 646131)
 (vectors 16 14337)
 (vector-slots 8 288368 17073)
 (floats 8 22 39)
 (intervals 56 262 0)
 (buffers 992 11))