only first private_network is used

this will prevent using last private_network for the hostname

lib/vagrant-hostmanager/hosts_file.rb

@@ -104,7 +104,7 @@ module VagrantPlugins
             machine.config.vm.networks.each do |network|
               key, options = network[0], network[1]
               ip = options[:ip] if key == :private_network
-              next if ip
+              break if ip
             end
           end
           ip || (machine.ssh_info ? machine.ssh_info[:host] : nil)