discover: log the actual HTTP port that is used.

If the default port is used (i.e. no command line argument specified),
this logging incorrectly reports the server is running at port 0.

connect/src/discovery.rs

@@ -231,7 +231,6 @@ pub fn discovery(
 
     let serve = {
         let http = Http::new();
-        debug!("Zeroconf server listening on 0.0.0.0:{}", port);
         http.serve_addr_handle(
             &format!("0.0.0.0:{}", port).parse().unwrap(),
             &handle,
@@ -240,6 +239,7 @@ pub fn discovery(
     };
 
     let s_port = serve.incoming_ref().local_addr().port();
+    debug!("Zeroconf server listening on 0.0.0.0:{}", s_port);
 
     let server_future = {
         let handle = handle.clone();