virtualbox: only configure networks if there are some [GH-1796]

CHANGELOG.md

@@ -20,6 +20,9 @@ IMPROVEMENTS:
     as well as V2 configuration.
   - Add `ARPCHECK=0` to RedHat OS family network configuration. [GH-1815]
   - Add SSH agent forwarding sample to initial Vagrantfile. [GH-1808]
+  - VirtualBox: Only configure networks if there are any to configure.
+    This allows linux's that don't implement this capability to work with
+    Vagrant. [GH-1796]
 
 BUG FIXES:
 

plugins/providers/virtualbox/action/network.rb

@@ -111,8 +111,10 @@ module VagrantPlugins
 
             # Only configure the networks the user requested us to configure
             networks_to_configure = networks.select { |n| n[:auto_config] }
-            env[:ui].info I18n.t("vagrant.actions.vm.network.configuring")
-            env[:machine].guest.capability(:configure_networks, networks_to_configure)
+            if !networks_to_configure.empty?
+              env[:ui].info I18n.t("vagrant.actions.vm.network.configuring")
+              env[:machine].guest.capability(:configure_networks, networks_to_configure)
+            end
           end
         end