fix test - stop scheduler threads separately.

src/init.cpp

@@ -214,10 +214,13 @@ void Shutdown()
 
     StopTorControl();
 
-    // After everything has been shut down, but before things get flushed, stop the
-    // CScheduler/checkqueue, scheduler and load block thread. 
+    // After everything has been shut down, but before things get flushed,
+    //1. stop the checkqueue threads.
     StopScriptCheckWorkerThreads();
 
+    //2. stop scheduler and load block threads.
+    scheduler.stop();
+
     // After the threads that potentially access these pointers have been stopped,
     // destruct and reset all to nullptr.
     peerLogic.reset();