21.4.6 crash in regex.c

21.4.6 crashes reproducibly when running Gnus and trying to inhale the following message, which happens to be in charset=gb2312. (It's included here as just an octet-stream, to avoid crashing anyone who is using Gnus on this list.) A search in regex.c falls through to the default "abort()" case. uname -a: Linux cinnamon.vanillaknot.com 2.4.9-12 #1 Tue Oct 30 18:33:49 EST 2001 i686 unknown ./configure '--with-pop' '--with-mule' '--error-checking=none' '--debug=no' '--with-ipv6-cname=no' '--with-sound=native,esd' '--memory-usage-stats' '--with-dialogs=athena' '--with-widgets=athena' '--with-athena=3d' XEmacs 21.4.6 "Common Lisp" configured for `i686-pc-linux'. Compilation / Installation: Source code location: /usr/src/Packages/xemacs/xemacs-21.4.6 Installation prefix: /usr/local Operating system description file: `s/linux.h' Machine description file: `m/intel386.h' Compiler: /usr/bin/gcc -g -O3 -Wall -Wno-switch -Winline -Wmissing-prototypes -Wsign-compare -Wshadow Relocating allocator for buffers: no GNU version of malloc: yes - Using Doug Lea's new malloc from the GNU C Library. Window System: Compiling in support for the X window system: - X Windows headers location: /usr/X11R6/include - X Windows libraries location: /usr/X11R6/lib - Handling WM_COMMAND properly. Compiling in support for the Athena widget set: - Athena headers location: X11/Xaw3d - Athena library to link: Xaw3d Using Lucid menubars. Using Lucid scrollbars. Using Athena dialog boxes. Using Athena native widgets. TTY: Compiling in support for ncurses. Compiling in support for GPM (General Purpose Mouse). Images: Compiling in support for GIF images (builtin). Compiling in support for XPM images. Compiling in support for PNG images. Compiling in support for JPEG images. Compiling in support for TIFF images. Compiling in support for X-Face message headers. Sound: Compiling in support for sound (native). Compiling in support for ESD (Enlightened Sound Daemon). Databases: Compiling in support for GNU DBM. Compiling in support for LDAP. Compiling in support for PostgreSQL. - Using PostgreSQL header file: pgsql/libpq-fe.h - Using PostgreSQL V7 bindings. Internationalization: Compiling in support for Mule (multi-lingual Emacs). Compiling in support for XIM (X11R5+ I18N input method). - Using raw Xlib to provide XIM support. Mail: Compiling in support for POP mail retrieval. Compiling in support for "dot-locking" mail spool file locking method. Other Features: Inhibiting IPv6 canonicalization at startup. Compiling in support for dynamic shared object modules.