bug#40240: 26.3; Wrong symbol inserted from keyboard: left tack instead of turnstile.

[Ignat Insarov <kindaro@gmail.com>]

When I type `⊢` (Unicode right tack, also called «turnstile»), the left
tack symbol appears instead. I can insert the turnstile with other
methods without problem.

Note that I have a key bound on my keyboard layout directly to this
symbol. It works across my system, with the sole exception of Emacs.

I suppose the volunteer will have to put the turnstile symbol onto their
keyboard layout. Try to insert turnstile directly from keyboard layout.
* Expected behaviour: a turnstile appears.
* Observed behaviour: left tack appears.

In GNU Emacs 26.3 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.10)
 of 2019-08-29 built on juergen

Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --with-x-toolkit=gtk3 --with-xft --with-modules
 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fno-plt'
 CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'

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

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