Launch error with empty host for a node

[eile]

The setup:

node
{
#    host     "bbplxviz13"
    connection
    {
         hostname      "bbplxviz13"
         filename      "default"
    }
}

will auto-launch the node on 127.0.0.1 which is not bbplxviz13. The reason is that the node's host is empty and the launcher guesses it to be 127.0.0.1. The user forgot to add the commented line, but the resulting behaviour is not easy to debug. Later on Equalizer would try to auto-launch on all connection hostnames, but since the first launch actually starts the client, it doesn't try anymore.