shopt can't set extglob in a sub-shell?

[Davide Baldini]

Configuration Information [Automatically generated, do not change]:
Machine: i486
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i486' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i486-pc-linux-gnu' 
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL 
-DHAVE_CONFIG_H   -I.  -I../bash -I../bash/include -I../bash/lib   -g -O2 -Wall
uname output: Linux debianBunker 2.6.26-2-686 #1 SMP Wed Sep 21 04:35:47 UTC 
2011 i686 GNU/Linux
Machine Type: i486-pc-linux-gnu

Bash Version: 4.1
Patch Level: 5
Release Status: release

Description:
        A 'test.sh` script file composed exclusively of the following text
        fails execution:
                #!/bin/bash
                (
                        shopt -s extglob
                        echo !(x)
                )
        giving the output:
                $ ./test.sh
                ./test.sh: line 4: syntax error near unexpected token `('
                ./test.sh: line 4: `    echo !(x)'
        Moving the shopt line above the sub-shell parenthesis makes the script
        work.

        The debian man pages give no explanation.

        Thank you.

Repeat-By:
        --
Fix:
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