searches: only remove old expired nodes

src/dht.cpp

@@ -610,7 +610,8 @@ Dht::Search::removeExpiredNode(time_point now)
     auto e = nodes.end();
     while (e != nodes.cbegin()) {
         e = std::prev(e);
-        if (e->node->isExpired(now)) {
+        const Node& n = *e->node;
+        if (n.isExpired(now) and n.time + NODE_EXPIRE_TIME < now) {
             nodes.erase(e);
             return true;
         }