bug#4251: 23.1.50; Error byte-compiling big conditional

[Aemon Cannon <aemoncannon@gmail.com>]

Received the following error:
bytecomp-bug.el:9:4:Error: Args out of range: 312, 0, 255

When byte-compiling a file with the following elisp:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defmacro many-forms ()
  (let ((body '()))
    (dotimes (i 20000)
      (setq body (cons '(message "more") body)))
    `(progn ,@body)))

(if (eq 1 a)
    (many-forms)
  (message "else"))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

Suspect a byte overflow at line 856 in bytecomp.el
The argument of a goto is bigger than 16 bits.



In GNU Emacs 23.1.50.1 (i486-pc-linux-gnu, GTK+ Version 2.16.1)
 of 2009-07-31 on lansones, modified by Debian
 (emacs-snapshot package, version 1:20090730-1~jaunty1)
Windowing system distributor `The X.Org Foundation', version 11.0.10600000
configured using `configure  '--build' 'i486-linux-gnu' '--host'
'i486-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib'
'--libexecdir=/usr/lib' '--localstatedir=/var'
'--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes'
'--enable-locallisppath=/etc/emacs-snapshot:/etc/emacs:/usr/local/share/emacs/23.1.50/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.1.50/site-lisp:/usr/share/emacs/site-lisp'
'--with-x=yes' '--with-x-toolkit=gtk' 'build_alias=i486-linux-gnu'
'host_alias=i486-linux-gnu' 'CFLAGS=-DDEBIAN
-DSITELOAD_PURESIZE_EXTRA=5000 -g -O2' 'LDFLAGS=-g -Wl,--as-needed'
'CPPFLAGS=''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t

Major mode: Emacs-Lisp

Minor modes in effect:
  shell-dirtrack-mode: t
  diff-auto-refine-mode: t
  show-paren-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t
  abbrev-mode: t