also sort results for empty patterns

there are no scores in this case, but it still makes tiebreak handling
more consistent

src/worker.rs

@@ -166,7 +166,10 @@ impl<T: Sync + Send + 'static> Worker<T> {
         if self.pattern.is_empty() {
             self.reset_matches();
             self.process_new_items_trivial();
-            if self.should_notify.load(atomic::Ordering::Relaxed) {
+            let canceled = self.sort_matches();
+            if canceled {
+                self.was_canceled = true;
+            } else if self.should_notify.load(atomic::Ordering::Relaxed) {
                 (self.notify)();
             }
             return;