Fix breakages when upgrading to babel 6

Reviewed By: vjeux

Differential Revision: D2628092

fb-gh-sync-id: 077a3572fe8b261d390be2bdc32d9d06c2b80a01

local-cli/bundle/__tests__/saveBundleAndMap-test.js

@@ -8,12 +8,10 @@
  */
 'use strict';
 
-jest
-  .dontMock('../saveBundleAndMap')
-  .dontMock('os-tmpdir')
-  .dontMock('temp');
+jest.autoMockOff();
 
 jest.mock('fs');
+jest.mock('../sign');
 
 const saveBundleAndMap = require('../saveBundleAndMap');
 const fs = require('fs');