Fix VecDeque's rotate_left and rotate_right panic tests

Author: pedroclobo

library/alloc/src/collections/vec_deque/tests.rs

@@ -351,14 +351,14 @@ fn test_rotate_left_right() {
 }
 
 #[test]
-#[should_panic = "assertion failed: mid <= self.len()"]
+#[should_panic = "assertion failed: n <= self.len()"]
 fn test_rotate_left_panic() {
     let mut tester: VecDeque<_> = (1..=10).collect();
     tester.rotate_left(tester.len() + 1);
 }
 
 #[test]
-#[should_panic = "assertion failed: k <= self.len()"]
+#[should_panic = "assertion failed: n <= self.len()"]
 fn test_rotate_right_panic() {
     let mut tester: VecDeque<_> = (1..=10).collect();
     tester.rotate_right(tester.len() + 1);