Fix ClientReplicationStreamProtocol.__str__ (#4929)

`__str__` depended on `self.addr`, which was absent from
ClientReplicationStreamProtocol, so attempting to call str on such an object
would raise an exception.

We can calculate the peer addr from the transport, so there is no need for addr
anyway.

changelog.d/4929.misc

@@ -0,0 +1 @@
+Fix `ClientReplicationStreamProtocol.__str__()`.

synapse/replication/tcp/protocol.py

@@ -375,8 +375,11 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
             self.transport.unregisterProducer()
 
     def __str__(self):
+        addr = None
+        if self.transport:
+            addr = str(self.transport.getPeer())
         return "ReplicationConnection<name=%s,conn_id=%s,addr=%s>" % (
-            self.name, self.conn_id, self.addr,
+            self.name, self.conn_id, addr,
         )
 
     def id(self):
@@ -392,12 +395,11 @@ class ServerReplicationStreamProtocol(BaseReplicationStreamProtocol):
     VALID_INBOUND_COMMANDS = VALID_CLIENT_COMMANDS
     VALID_OUTBOUND_COMMANDS = VALID_SERVER_COMMANDS
 
-    def __init__(self, server_name, clock, streamer, addr):
+    def __init__(self, server_name, clock, streamer):
         BaseReplicationStreamProtocol.__init__(self, clock)  # Old style class
 
         self.server_name = server_name
         self.streamer = streamer
-        self.addr = addr
 
         # The streams the client has subscribed to and is up to date with
         self.replication_streams = set()

synapse/replication/tcp/resource.py

@@ -57,7 +57,6 @@ class ReplicationStreamProtocolFactory(Factory):
             self.server_name,
             self.clock,
             self.streamer,
-            addr
         )