Emacs 21.3, Linux tty: Meta gets lopped off of C-M-g

[Alan Mackenzie <acm@muc.de>]

In GNU Emacs 21.3.1 (i686-pc-linux-gnulibc1, X toolkit, Xaw3d scroll bars)
 of 2003-10-25 on acm
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: en_GB
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: nil
  locale-coding-system: iso-latin-1
  default-enable-multibyte-characters: t

At Emacs 21.3 on a Linux tty, something in Emacs's low-level keyboard
handling appears to be mangling the key event C-M-g, silently discarding
the "M-", leaving C-g.  To see this, type C-h c C-M-g.  In the echo area
appears:

C-g runs the command keyboard-quit

This is wrong.  What should appear is:

ESC C-g is undefined

Of the C-M-<english-letter> key presses, the other 25 make it through
Emacs's low-level keyboard processing unscathed.  Only C-M-g doesn't.  For
comparison, on typing C-h c C-M-z, what appears (correctly) is

ESC C-z is undefined

For further comparison, when this Emacs is running under X-Windows,
typing C-M-g correctly causes the following to appear in the echo area:

C-M-g is undefined

-- 
Alan Mackenzie (Munich, Germany)