make sure that thing get closed down properly..

multicast.py

@@ -27,6 +27,12 @@ class StupidProtocol(object):
 	def __init__(self):
 		self.transport = None
 
+	def close(self):
+		return self.transport.close()
+
+	def connection_lost(self, exc):
+		self.transport = None
+
 	def connection_made(self, transport):
 		# Note: the connection_made call seems to be sync.  This
 		# isn't documented, and I don't know how to force a test
@@ -89,3 +95,7 @@ class TestMulticast(unittest.IsolatedAsyncioTestCase):
 
 		self.assertEqual((await l1.recv())[0], msg)
 		self.assertEqual((await l2.recv())[0], msg)
+
+		t1.close()
+		l1.close()
+		l2.close()