Always store values even when not registered

lib/vagrant/config/v2/root.rb

@@ -29,13 +29,14 @@ module Vagrant
           if config_klass
             # Instantiate the class and return the instance
             @keys[name] = config_klass.new
-            return @keys[name]
           else
             @logger.debug("missing key request name=#{name} loc=#{caller.first}")
             # Record access to a missing key as an error
             @missing_key_calls.add(name.to_s)
-            return DummyConfig.new
+            @keys[name] = DummyConfig.new
           end
+
+          @keys[name]
         end
 
         # Called to finalize this object just prior to it being used by