bug#37163: 27.0.50; grep command no colors

[Ergus]

--text follows this line--

In the current emacs master breanch I am trying to use the grep command
and the execution is fine but the output *grep* buffer doesn't contain
the colors, it shows the scape sequences.

I have tried in my actual installation of emacs 26 and the issue is not
there, only in emacs 27. In gui and tui the behavior is the same.

Example:

M-x grep REP
grep --color -nH --null -e display xdisp.c 

===================================================
-*- mode: grep; default-directory: "~/gits/emacs/src/" -*-
Grep started at Fri Aug 23 19:08:10

grep --color -nH --null -e display xdisp.c 
xdisp.c21:/* New redisplay written by Gerd Moellmann <gerd@gnu.org>.
xdisp.c23:   Redisplay.
xdisp.c25:   Emacs separates the task of updating the display from 
code
xdisp.c28:   the display.
xdisp.c30:   Updating the display is triggered by the Lisp 
interpreter when it
xdisp.c33:   calling Lisp functions like `sit-for'.  The C function 
`redisplay'
xdisp.c34:   in xdisp.c is the only entry into the inner redisplay 
code.
xdisp.c36:   The following diagram shows how redisplay code is 
invoked.  As you
xdisp.c37:   can see, Lisp calls redisplay and vice versa.
xdisp.c39:   Under window systems like X, some portions of the 
redisplay code
xdisp.c43:   redisplay via expose_frame and/or 
note_mouse_highlight, if X events

=====================================================


In GNU Emacs 27.0.50 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.10)
of 2019-08-23 built on Ergus
Repository revision: b4065de33cf397b80e15c22740d34b4a03cfdc17
Repository branch: master
System Description: Arch Linux

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Quit
start-file-process-shell-command: Invalid function: 
with-connection-local-variables
Configured using:
'configure --prefix=/mnt/casa/install_arch/emacs --with-x-toolkit=gtk3
--with-xft --with-modules --with-mailutils'

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND GPM DBUS GSETTINGS GLIB NOTIFY INOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE HARFBUZZ M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS LIBSYSTEMD JSON
PDUMPER LCMS2 GMP

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

Major mode: C/*l

Minor modes in effect:
 shell-dirtrack-mode: t
 bug-reference-prog-mode: t
 tooltip-mode: t
 global-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
 abbrev-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
format-spec rfc822 mml mml-sec password-cache epa derived epg epg-config
gnus-util rmail rmail-loaddefs text-property-search time-date subr-x seq
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
mail-utils files-x shell pcomplete thingatpt grep compile comint
ansi-color ring vc-git diff-mode easy-mmode bug-reference cc-mode
cc-fonts easymenu cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine
cc-vars cc-defs cl-loaddefs cl-lib term/tmux term/xterm xterm byte-opt
gv bytecomp byte-compile cconv tooltip eldoc electric uniquify
ediff-hook vc-hooks lisp-float-type mwheel term/x-win x-win
term/common-win x-dnd 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 threads dbusbind inotify lcms2 dynamic-setting
system-font-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty make-network-process emacs)

Memory information:
((conses 16 91980 7054)
(symbols 48 9859 1)
(strings 32 26288 2139)
(string-bytes 1 963910)
(vectors 16 12708)
(vector-slots 8 132886 5840)
(floats 8 31 471)
(intervals 56 2931 0)
(buffers 992 13))