Post-review fix.

sql/sp_head.cc:
  Post-review fix; changed string copying method (+ fixed comment typo and indention).

sql/sp_head.cc

@@ -295,7 +295,7 @@ sp_eval_func_item(THD *thd, Item **it_addr, enum enum_field_types type,
 
     /*
       For some functions, 's' is now pointing to an argument of the
-      function, which might be a local variable that it to be reused.
+      function, which might be a local variable that is to be reused.
       In this case, new(reuse, &rsize) below will call the destructor
       and 's' ends up pointing to freed memory.
       A somewhat ugly fix is to simply copy the string to our local one
@@ -304,7 +304,8 @@ sp_eval_func_item(THD *thd, Item **it_addr, enum enum_field_types type,
      */
     if (reuse && s != &tmp && s != &it->str_value)
     {
-      tmp.copy(s->c_ptr(), s->length(), it->collation.collation);
+      if (tmp.copy((const String)(*s)))
+        DBUG_RETURN(NULL);
       s= &tmp;
     }
 
@@ -338,7 +339,7 @@ sp_eval_func_item(THD *thd, Item **it_addr, enum enum_field_types type,
 
 return_null_item:
   CREATE_ON_CALLERS_ARENA(it= new(reuse, &rsize) Item_null(),
-                    use_callers_arena, &backup_arena);
+                          use_callers_arena, &backup_arena);
 end:
   it->rsize= rsize;