I've attempted to reproduce 5404 on Mac OS X 10.6.4  with

   GNU Emacs 23.2.91.1 (x86_64-apple-darwin10.4.0, NS apple-appkit-1038.32) of 2011-01-02

and

   (146:1)oatmeal.ma.runwaynine.com:~$ gdb --version
   GNU gdb 6.3.50-20050815 (Apple version gdb-1469) (Wed May  5 04:36:56 UTC 2010)
   Copyright 2004 Free Software Foundation, Inc.
   GDB is free software, covered by the GNU General Public License, and you are
   welcome to change it and/or distribute copies of it under certain conditions.
   Type "show copying" to see the conditions.
   There is absolutely no warranty for GDB.  Type "show warranty" for details.
   This GDB was configured as "x86_64-apple-darwin"

The behavior reported in 5404 does NOT occur in this configuration.