core: MachineIndex#valid? checks state and ID again

lib/vagrant/machine_index.rb

@@ -435,11 +435,19 @@ module Vagrant
         # found, it is already false.
         return false if !found
 
-        # If the environment doesn't contain the machine with this
-        # name, then it is also false. At some point, we can remove
-        # this limitation if we support destroying machines where
-        # the Vagrantfile is moved.
-        return false if !env.machine_names.find { |n| n == self.name.to_sym }
+        # Get the machine
+        machine = nil
+        begin
+          machine = env.machine(self.name.to_sym, self.provider.to_sym)
+        rescue Errors::MachineNotFound
+          return false
+        end
+
+        # Refresh the machine state
+        machine.state
+
+        # If the machine doesn't have an ID, it is invalid
+        return false if !machine.id
 
         true
       end

plugins/providers/virtualbox/provider.rb

@@ -73,15 +73,17 @@ module VagrantPlugins
       #
       # @return [Symbol]
       def state
-        # XXX: What happens if we destroy the VM but the UUID is still
-        # set here?
-
         # Determine the ID of the state here.
         state_id = nil
         state_id = :not_created if !@driver.uuid
         state_id = @driver.read_state if !state_id
         state_id = :unknown if !state_id
 
+        # If we're not created, then reset the ID to nil
+        if state_id == :not_created
+          @machine.id = nil
+        end
+
         # Translate into short/long descriptions
         short = state_id.to_s.gsub("_", " ")
         long  = I18n.t("vagrant.commands.status.#{state_id}")