regex in bashexpression doesn't work

[Niels Carl W. Hansen]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-redhat-linux-gnu' 
-DCONF_VENDOR='redhat' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL 
-DHAVE_CONFIG_H   -I.  -I. -I./include -I./lib  -D_GNU_SOURCE -DRECYCLES_PIDS  
-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector 
--param=ssp-buffer-size=4 -m64 -mtune=generic -fwrapv
uname output: Linux in 2.6.32-220.17.1.el6.x86_64 #1 SMP Wed May 16 00:01:37 
BST 2012 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-redhat-linux-gnu

Bash Version: 4.1
Patch Level: 2
Release Status: release

Description:
        [[ 'foobar'  =~ 'o.a' ]] && echo FOUND
        should print  FOUND  but it doesn't.
        This have worked in previeous versions of bash.
        The bash used comes with CentOS 6.2

Repeat-By:
        No privous commands necessary to generate this problem.

Fix: