Don't require root path to load an environment. (Makes `vagrant box` commands work again without a Vagrantfile)

lib/vagrant/command/helpers.rb

@@ -12,6 +12,8 @@ module Vagrant
       # This returns an array of {VM} objects depending on the arguments
       # given to the command.
       def target_vms(name=nil)
+        raise Errors::NoEnvironmentError.new if !env.root_path
+
         name ||= self.name rescue nil
 
         @target_vms ||= begin

lib/vagrant/environment.rb

@@ -220,7 +220,6 @@ module Vagrant
     def load!
       if !loaded?
         @loaded = true
-        raise Errors::NoEnvironmentError.new if !root_path
         self.class.check_virtualbox!
         load_config!
         load_vm!
@@ -242,7 +241,7 @@ module Vagrant
       loader.queue << File.expand_path("config/default.rb", Vagrant.source_root)
       loader.queue << File.join(box.directory, ROOTFILE_NAME) if !first_run && box
       loader.queue << File.join(home_path, ROOTFILE_NAME) if !first_run && home_path
-      loader.queue << File.join(root_path, ROOTFILE_NAME)
+      loader.queue << File.join(root_path, ROOTFILE_NAME) if root_path
 
       # If this environment is representing a sub-VM, then we push that
       # proc on as the last configuration.

test/vagrant/command/helpers_test.rb

@@ -27,7 +27,14 @@ class CommandHelpersTest < Test::Unit::TestCase
   context "vms from args" do
     setup do
       @env = vagrant_env
-      @env.stubs(:root_path).returns(7)
+    end
+
+    should "raise an exception if no root path" do
+      @env.stubs(:root_path).returns(nil)
+
+      assert_raises(Vagrant::Errors::NoEnvironmentError) {
+        command([], @env).target_vms
+      }
     end
 
     should "only calculate the result once" do