Fix regression from 6b317395 regarding...

Fix regression from 6b317395 regarding connectivity to unconfigured cluster nodes.

StackExchange.Redis/StackExchange/Redis/ClusterConfiguration.cs

@@ -315,6 +315,12 @@ internal ClusterNode(ClusterConfiguration configuration, string raw, EndPoint or
             var flags = parts[2].Split(StringSplits.Comma);
             
             endpoint = Format.TryParseEndPoint(parts[1]);
+            if (endpoint == null && flags.Contains("myself"))
+            {
+                // Unconfigured cluster nodes might report themselves as endpoint ":{port}",
+                // hence the origin fallback value to make sure that we can address them
+                endpoint = origin;
+            }
 
             nodeId = parts[0];
             isSlave = flags.Contains("slave");