The list comp patch checked for the second child node of the 'listmaker'

node, without checking if the node actually had more than one child. It can
have only one node, though: '[' test ']'. This fixes it.

Python/compile.c

@@ -1045,7 +1045,7 @@ static void
 com_listmaker(struct compiling *c, node *n)
 {
 	/* listmaker: test ( list_iter | (',' test)* [','] ) */
-	if (TYPE(CHILD(n, 1)) == list_iter)
+	if (NCH(n) > 1 && TYPE(CHILD(n, 1)) == list_iter)
 		com_list_comprehension(c, n);
 	else {
 		int len = 0;