Revert "allow Optional int for port"

The type change was made in #420, and we don't want to rearrange the
handling of `port is None`.

This reverts commit b464459.

sydent/replication/peer.py

@@ -132,17 +132,15 @@ def __init__(
         :param lastSentVersion: The ID of the last association sent to the peer.
         """
         super().__init__(server_name, pubkeys)
-
-        if port is None:
-            port = 1001
-
         self.sydent = sydent
         self.lastSentVersion = lastSentVersion
 
         # look up or build the replication URL
         replication_url = self.sydent.config.http.base_replication_urls.get(server_name)
 
         if replication_url is None:
+            if not port:
+                port = 1001
             replication_url = "https://%s:%i" % (server_name, port)
 
         if replication_url[-1:] != "/":