${assoc[key]+set} no longer works.

[geir . hauge]

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-unknown-linux-gnu' 
-DCONF_VENDOR='unknown' -DLOCALEDIR='/usr/local/share/locale' -DPACKAGE='bash' 
-DSHELL -DHAVE_CONFIG_H   -I.  -I. -I./include -I./lib   -g -O2
uname output: Linux gina 3.2.0-59-generic #90-Ubuntu SMP Tue Jan 7 22:43:51 UTC 
2014 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-unknown-linux-gnu

Bash Version: 4.3
Patch Level: 0
Release Status: release

Description:
    With an associative array, assoc, ${assoc[key]+set} expands to the
    empty string if the associated value is the empty string.

Repeat-By:
    $ declare -A assoc='([x]= [y]="1" )'
    $ printf '<%s>\n' "${assoc[x]+x is a key}" "${assoc[y]+y is a key}"
    <>
    <y is a key>