When starting a standalone roxie process with Dali, if a query creates a file, it uses the implicit group name ".".
However, addCluster assumes it is running on 1 node of the group and postfixes the groupname with the indexed position e.g. myroxie
But "." is not a published group name, and it has a width of 1.
Fix by avoiding postfix with index position if group is only 1 node in size.