free: called with unallocated block argument

[phil]

Configuration Information [Automatically generated, do not change]:
Machine: i686
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i686' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i686-pc-linux-gnu' 
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL 
-DHAVE_CONFIG_H   -I.  -I. -I./include -I./lib   -g -O2
uname output: Linux Arcturus 2.6.27.15jpmr #20 SMP Sun Feb 8 12:51:35 CET 2009 
i686 GNU/Linux
Machine Type: i686-pc-linux-gnu

Bash Version: 4.0
Patch Level: 0
Release Status: release

Description:
Problem with auto completion :
        ls[space][TAB]
gives the follwing abort :
        malloc: /Users/chet/src/bash/src/parse.y:5561: assertion botched
        free: called with unallocated block argument
        last command: ls
        Aborting...Abandon

If /etc/bash_completion is suppressed, problem disapears.
My bash_completion is : 
        $Id: bash_completion,v 1.872 2006/03/01 16:20:18 ianmacd Exp $

Repeat-By:
        ls[space] [TAB]
or 
        cd[space][TAB]
and several other commands.