Avoid computing patch_root in get_files_affected_by_patch.

recipe_modules/tryserver/example.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 DEPS = [
   'recipe_engine/path',
   'recipe_engine/platform',
   'recipe_engine/properties',
   'recipe_engine/python',
   'tryserver',
 ]
 
 
 def RunSteps(api):
   api.path['checkout'] = api.path['slave_build']
   api.tryserver.maybe_apply_issue()
-  api.tryserver.get_files_affected_by_patch()
+  api.tryserver.get_files_affected_by_patch(
+      api.properties.get('test_patch_root'))
 
   if api.tryserver.is_tryserver:
     api.tryserver.set_subproject_tag('v8')
 
   api.tryserver.set_patch_failure_tryjob_result()
   api.tryserver.set_compile_failure_tryjob_result()
   api.tryserver.set_test_failure_tryjob_result()
   api.tryserver.set_invalid_test_results_tryjob_result()
 
   with api.tryserver.set_failure_hash():
     api.python.failing_step('fail', 'foo')
 
 
 def GenTests(api):
   yield (api.test('with_svn_patch') +
          api.properties(patch_url='svn://checkout.url'))
 
   yield (api.test('with_git_patch') +
          api.properties(
               patch_storage='git',
               patch_project='v8',
               patch_repo_url='http://patch.url/',
               patch_ref='johndoe#123.diff'))
 
   yield (api.test('with_rietveld_patch') +
          api.properties.tryserver())
 
   yield (api.test('with_wrong_patch') + api.platform('win', 32))
+
+
+  yield (api.test('with_rietveld_patch_new') +
+         api.properties.tryserver(test_patch_root='sub/project'))
+
+  yield (api.test('with_wrong_patch_new') + api.platform('win', 32) +
+         api.properties(test_patch_root='sub\\project'))