Fix crashing issue when all networks don't aut config [GH-689]

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## 0.9.5 (unreleased)
 
-
+  - Fix crashing case when all network options are `:auto_config false`.
+    [GH-689]
 
 ## 0.9.4 (January 28, 2012)
 

lib/vagrant/action/vm/network.rb

@@ -64,7 +64,7 @@ module Vagrant
           # setup until after it is booted.
           @app.call(env)
 
-          if !adapters.empty?
+          if !adapters.empty? && !networks.empty?
             # Determine the interface numbers for the guest.
             assign_interface_numbers(networks, adapters)