Incompatibility between bash versions running a configure script

[pauli]

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
uname output: Linux skaro 2.4.27-2-k7 #1 Wed Nov 30 22:12:04 JST 2005 i686 
GNU/Linux
Machine Type: i486-pc-linux-gnu

Bash Version: 3.1
Patch Level: 14
Release Status: release

Description:
        Incompatibility running a configure script.

        The script appears to work fine from bash version:
                GNU bash, version 2.05b.0(1)-release (i386-pc-linux-gnu)
        but when I run it on version:
                GNU bash, version 3.1.14(1)-release (i486-pc-linux-gnu)
        I get:

-------------------------------------8<---------------------------------------
checking system version (for dynamic loading)... ./configure: line 1379: syntax 
error near unexpected token `('
./configure: line 1379: `  case `(ac_space=' '; set) 2>&1` in'
-------------------------------------8<---------------------------------------


Repeat-By:
        I'm attempting to build the PAM Samba module available from:
                http://www.csn.ul.ie/~airlied/pam_smb/

        Specifically this archive:
                http://pamsmb.sourceforge.net/v1/pam_smb-1.1.7.tar.gz


I'm getting the error on the second line (1379) of this mess:

-------------------------------------8<---------------------------------------
(set) 2>&1 |
  case `(ac_space=' '; set) 2>&1` in
  *ac_space=\ *)
    # `set' does not quote correctly, so add quotes (double-quote substitution
    # turns \\\\ into \\, and sed turns \\ into \).
    sed -n \
      -e "s/'/'\\\\''/g" \
      -e "s/^\\([a-zA-Z0-9_]*_cv_[a-zA-Z0-9_]*\\)=\\(.*\\)/\\1=\${\\1='\\2'}/p"
    ;;
  *)
    # `set' quotes correctly as required by POSIX, so do not add quotes.
    sed -n -e 's/^\([a-zA-Z0-9_]*_cv_[a-zA-Z0-9_]*\)=\(.*\)/\1=${\1=\2}/p'
    ;;
  esac >> confcache
-------------------------------------8<---------------------------------------