DepotDownloader: Suppress CellID 0 warning if using auth (as CellID will be automatically retrieved).

DepotDownloader/Program.cs

@@ -62,10 +62,13 @@ namespace DepotDownloader
             if (cellId == -1)
             {
                 cellId = 0;
+                if (GetStringParameter(args, "-username") == null)
+                {
                     Console.WriteLine(
                         "Warning: Using default CellID of 0! This may lead to slow downloads. " +
                         "You can specify the CellID using the -cellid parameter");
                 }
+            }
 
             ContentDownloader.Config.CellID = cellId;