f fix msrv

Author: TheBlueMatt

lightning/src/util/wakers.rs

@@ -262,7 +262,7 @@ impl Sleeper {
 				if let Some(notified_fut) = notified_fut_lck.take() {
 					break notified_fut;
 				}
-				let sleep_time = max_wait.saturating_sub(start_time.elapsed());
+				let sleep_time = max_wait.checked_sub(start_time.elapsed()).unwrap_or(Duration::from_secs(0));
 				if sleep_time == Duration::from_secs(0) { return false; }
 				notified_fut_lck = cv.wait_timeout(notified_fut_lck, max_wait).unwrap().0;
 			}