behavior diff. btw. 3.0 and 3.1 (may be a bug)

[vw]

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   -O2 -march=i686 
-fomit-frame-pointer -pipe -w
uname output: Linux wst07 2.6.15.1 #1 SMP PREEMPT Sat Jan 21 15:06:51 CET 2006 
i686 pentium4 i386 GNU/Linux
Machine Type: i686-pc-linux-gnu

Bash Version: 3.1
Patch Level: 5
Release Status: release

Description:
        There is a behavior difference between bash 3.0 and 3.1. This results
        in trouble installing oracle database software. in 3.0 `cmd` can
        span over lines, in 3.1 not.

Repeat-By:
        
a=`echo 'a b c' | sed 's/ /\\
/g' | grep 'b'`
echo $a