unset associative array may cause segfault

[Roman Rakus]

reproducer:
declare -A aaa
aaa='somestring'
unset aaa

This commands cause segmentation fault, free unallocated memory.
Chet do you already fix it? Here is my fast patch.
RR

diff -up bash-4.0/hashlib.c.alloc bash-4.0/hashlib.c
--- bash-4.0/hashlib.c.alloc    2009-08-25 16:25:21.000000000 +0200
+++ bash-4.0/hashlib.c  2009-08-25 16:25:52.000000000 +0200
@@ -193,7 +193,7 @@ hash_search (string, table, flags)
       table->bucket_array[bucket] = list;
 
       list->data = NULL;
-      list->key = (char *)string;      /* XXX fix later */
+      list->key = (char *)savestring (string); /* XXX fix later */
       list->khash = hv;
       list->times_found = 0;