If the data store is empty, delete the backing file

lib/vagrant/data_store.rb

@@ -25,8 +25,11 @@ module Vagrant
       return if !file_path
 
       clean_nil_and_empties
-      File.open(file_path, "w") do |f|
-        f.write(to_json)
+
+      if empty?
+        File.delete(file_path) if File.file?(file_path)
+      else
+        File.open(file_path, "w") { |f| f.write(to_json) }
       end
     end
 

test/vagrant/data_store_test.rb

@@ -11,7 +11,7 @@ class DataStoreTest < Test::Unit::TestCase
   end
 
   teardown do
-    File.delete(@db_file)
+    File.delete(@db_file) if File.file?(@db_file)
   end
 
   should "be a hash with indifferent access" do
@@ -39,6 +39,17 @@ class DataStoreTest < Test::Unit::TestCase
     assert_equal "changed", @klass.new(@db_file)[:foo]
   end
 
+  should "delete the data store file if the hash is empty" do
+    @instance[:foo] = :bar
+    @instance.commit
+    assert File.exist?(@db_file)
+
+    @instance.clear
+    assert @instance.empty?
+    @instance.commit
+    assert !File.exist?(@db_file)
+  end
+
   should "clean nil and empties if commit is called" do
     @instance[:foo] = { :bar => nil }
     @instance[:bar] = {}