Shellshock fixes break job submission to "at"

Since the patches for shellshock have been applied to bash I can't submit jobs to "at".
I have a bash environment chuck full of functions, when I submit an "at" job bash aborts with an error message "File name too long"

System: 12.04
Bash: 4.2-2ubuntu2.

Example:

$> echo myjob.sh | at now

Results:

sh: 116: BASH_FUNC_form%%=() { while read; do
 args=;
 sp="";
 for i in "$@";
 do
 if [ "$i" == "%" ]; then
 sp="";
 continue;
 else
 if [ "$i" == "$" ]; then
 echo $args;
 args="";
 sp="";
 continue;
 fi;
 fi;
 if [ "${i:0:1}" != "@" ]; then
 args="$args$sp$i";
 else
 if [ "${i:1}" != "" ]; then
 args="$args$sp$( nth ${i:1} $REPLY)";
 else
 args="$args$sp$REPLY";
 fi;
 fi;
 sp=" ";
 done;
 echo $args;
 done
}: File name too long
sh: 116: export: BASH_FUNC_form%%: bad variable name