core: if state ID is NOT_CREATED_ID, destroy machine state

lib/vagrant/machine.rb

@@ -421,6 +421,12 @@ module Vagrant
       result = @provider.state
       raise Errors::MachineStateInvalid if !result.is_a?(MachineState)
 
+      # If the ID is the special not created ID, then set our ID to
+      # nil so that we destroy all our data.
+      if result.id == MachineState::NOT_CREATED_ID
+        self.id = nil
+      end
+
       # Update our state cache if we have a UUID and an entry in the
       # master index.
       uuid = index_uuid

lib/vagrant/machine_state.rb

@@ -14,6 +14,12 @@ module Vagrant
   # The long description can span multiple lines describing what the
   # state actually means.
   class MachineState
+    # This is a special ID that can be set for the state ID that
+    # tells Vagrant that the machine is not created. If this is the
+    # case, then Vagrant will set the ID to nil which will automatically
+    # clean out the machine data directory.
+    NOT_CREATED_ID = :not_created
+
     # Unique ID for this state.
     #
     # @return [Symbol]

test/unit/vagrant/machine_test.rb

@@ -627,6 +627,18 @@ describe Vagrant::Machine do
       expect(entry.state).to eq("short")
       env.machine_index.release(entry)
     end
+
+    it "should set the ID to nil if the state is not created" do
+      state = Vagrant::MachineState.new(
+       Vagrant::MachineState::NOT_CREATED_ID, "short", "long")
+
+      allow(provider).to receive(:machine_id_changed)
+      subject.id = "foo"
+
+      expect(provider).to receive(:state).and_return(state)
+      expect(subject.state.id).to eq(Vagrant::MachineState::NOT_CREATED_ID)
+      expect(subject.id).to be_nil
+    end
   end
 
   describe "#with_ui" do