darkirc: update event_graph synced flag when we were already on latest tip

src/event_graph/mod.rs

@@ -279,6 +279,7 @@ impl EventGraph {
         }
 
         if missing_parents.is_empty() {
+            *self.synced.write().await = true;
             info!(target: "event_graph::dag_sync()", "[EVENTGRAPH] DAG synced successfully!");
             return Ok(())
         }