Config class now properly uses class variables. Not sure how this one slipped through the cracks.

lib/vagrant/config.rb

@@ -4,21 +4,21 @@ module Vagrant
   end
 
   class Config
-    @config = nil
-    @config_runners = []
+    @@config = nil
+    @@config_runners = []
 
     class << self
       def reset!
-        @config = nil
+        @@config = nil
         config_runners.clear
       end
 
       def config
-        @config ||= Config::Top.new
+        @@config ||= Config::Top.new
       end
 
       def config_runners
-        @config_runners ||= []
+        @@config_runners ||= []
       end
 
       def run(&block)

test/test_helper.rb

@@ -20,8 +20,7 @@ require 'mocha'
 class Test::Unit::TestCase
   # Clears the previous config and sets up the new config
   def mock_config
-    Vagrant::Config.instance_variable_set(:@config_runners, nil)
-    Vagrant::Config.instance_variable_set(:@config, nil)
+    Vagrant::Config.reset!
 
     Vagrant::Config.run do |config|
       config.vagrant.dotfile_name = ".hobo"

test/vagrant/config_test.rb

@@ -38,8 +38,7 @@ class ConfigTest < Test::Unit::TestCase
 
   context "initializing" do
     teardown do
-      Vagrant::Config.instance_variable_set(:@config_runners, nil)
-      Vagrant::Config.instance_variable_set(:@config, nil)
+      Vagrant::Config.reset!
     end
 
     should "not run the blocks right away" do