Address GitLab issue #190: ntp.packet.ControlException in ntpsweep

ntpsweep/ntpsweep

@@ -171,8 +171,11 @@ Host                             st offset(s) version     system       processor
     known_host_peers = {}
     trace = []
     for host in hostlist:
-        scan_host(host, 0)
-
+        try:
+            scan_host(host, 0)
+        except ntp.packet.ControlException as e:
+            sys.stderr.write(e.message + "\n")
+            sys.exit(1)
     sys.exit(0)
 
 # end