substitution fails if it begins with *()

[bashbug]

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/loc
uname output: Linux celerypad 2.6.24-21-generic #1 SMP Sat Jul 26 15:39:24 UTC 
2008 i686 GNU/Linux
Machine Type: i486-pc-linux-gnu

Bash Version: 3.2
Patch Level: 39
Release Status: release

Description:
        if a *() is at the begin of a substitution, the substitution fails
        if the *() is preceeded by something, the substitution works

Repeat-By:
          $ r="z = y";echo ${r/*( )=*( )/=}          # *() at begin of 
substitution causes substitution to fail
        z = y
          $ r="z = y";echo ${r/ *( )=*( )/=}         # works if *() is 
preceeded by something
        z=y