diff -up bash-4.2/subst.c.old bash-4.2/subst.c

--- bash-4.2/subst.c.old	2015-12-09 13:24:47.369738319 +0100

+++ bash-4.2/subst.c	2015-12-09 13:28:27.366024824 +0100

@@ -2713,6 +2713,8 @@ do_compound_assignment (name, value, fla

       else if (v == 0 || (array_p (v) == 0 && assoc_p (v) == 0) || v->context != variable_context)

         v = make_local_array_variable (name);

       assign_compound_array_list (v, list, flags);

+      if (list)

+	dispose_words (list);

     }

   else

     v = assign_array_from_string (name, value, flags);