bash incorrectly calls completion function in certain circumstances

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-redhat-linux-gnu' 
-DCONF_VENDOR='redhat' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL 
-DHAVE_CONFIG_H  -I.  -I. -I./include -I./lib  -D_FILE_OFFSET_BITS=64 -O2 -g 
-pipe -march=i386 -mcpu=i686
uname output: Linux sagan.caliban.org 2.6.8.1 #1 SMP Sat Aug 28 13:07:48 PDT 
2004 i686 i686 i386 GNU/Linux
Machine Type: i686-redhat-linux-gnu

Bash Version: 3.0
Patch Level: 13
Release Status: release

Description:
        When a completion function is installed for a given command,
        attempting to complete the RHS of a variable assignment that
        uses that command's name will result in the completion function
        being erroneously invoked.

Repeat-By:
        An example:

        $ _gzip() { echo -e "\n$COMP_CWORD"; }
        $ complete -F _gzip gzip
        $ # Normal behaviour:
        $ gzip <Tab>
        1
        $ # The following, however, should not occur:
        $ foo=/tmp/gzip<Tab>
        0
        $
        
        As you can see, the _gzip() function is being invoked in an
        attempt to complete the RHS of the variable assignment. This
        should not happen, as gzip is not being invoked as a command
        here. Instead, normal file completion should occur.
        
        /tmp/gzip does not exist. If /bin/gzip is used instead, normal
        file completion _does_ occur.