Fix hang on exception

Author: stevenfontanella

check.py

@@ -293,10 +293,10 @@ def printer():
         # There's no concern of deadlocking during shutdown here.
         os._exit(1)
     finally:
-        executor.shutdown()
+        executor.shutdown(cancel_futures=True)
 
-    output_queue.shutdown()
-    printing_thread.join()
+        output_queue.shutdown()
+        printing_thread.join()
 
 
 def run_validator_tests():