Fix memory leak in owned_to_vec (#773)

tests/test_bytes.rs

@@ -1619,6 +1619,19 @@ fn owned_to_vec() {
     assert_eq!(drop_counter.get(), 1);
 }
 
+#[test]
+fn owned_into_vec() {
+    let drop_counter = SharedAtomicCounter::new();
+    let buf: [u8; 10] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+    let owner = OwnedTester::new(buf, drop_counter.clone());
+    let b1 = Bytes::from_owner(owner);
+
+    let v1: Vec<u8> = b1.into();
+    assert_eq!(&v1[..], &buf[..]);
+    // into() vec will copy out of the owner and drop it
+    assert_eq!(drop_counter.get(), 1);
+}
+
 #[test]
 #[cfg_attr(not(panic = "unwind"), ignore)]
 fn owned_safe_drop_on_as_ref_panic() {