Avoid nesting steps called under waiting for x:

scripts/slave/recipes/bisection/desktop_bisect.py

 # Copyright (c) 2015 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 = [
     'auto_bisect',
     'bisect_tester',
     'chromium',
     'chromium_tests',
     'depot_tools/gclient',
     'recipe_engine/json',
     'recipe_engine/path',
     'recipe_engine/platform',
     'recipe_engine/properties',
     'recipe_engine/raw_io',
     'recipe_engine/step',
 ]
 
 
 def RunSteps(api):
   mastername = api.properties.get('mastername')
   buildername = api.properties.get('buildername')
   # TODO(akuegel): Explicitly load the builder configs instead of relying on
   # builder.py from chromium_tests recipe module.
   bot_config = api.chromium_tests.create_bot_config_object(mastername,
                                                            buildername)
   api.chromium_tests.configure_build(bot_config)
   api.gclient.apply_config('perf')
+  # TODO(robertocn): remove do_not_nest_wait_for_revision once downstream
+  # expectations have been fixed, and make it behave like this by default.
   update_step, bot_db = api.chromium_tests.prepare_checkout(bot_config)
-  api.auto_bisect.start_try_job(api, update_step=update_step, bot_db=bot_db)
+  api.auto_bisect.start_try_job(api, update_step=update_step, bot_db=bot_db,
+                                do_not_nest_wait_for_revision=True)
 
 
 def GenTests(api):
   yield (api.test('basic') + api.properties.tryserver(
       mastername='tryserver.chromium.perf',
       buildername='linux_perf_bisect') + api.override_step_data(
           'git diff to analyze patch',
           api.raw_io.stream_output('tools/auto_bisect/bisect.cfg')))
 
   config_json = {
@@ skipping 166 matching lines @@
                                   buildername='linux_perf_bisect') +
          api.step_data('saving url to temp file',
                        stdout=api.raw_io.output('/tmp/dummy1')) + api.step_data(
                            'saving json to temp file',
                            stdout=api.raw_io.output('/tmp/dummy2')) +
          api.properties(bisect_config=bisect_ret_code_config) + api.properties(
              job_name='f7a7b4135624439cbd27fdd5133d74ec') +
          api.bisect_tester(tempfile='/tmp/dummy') + api.properties(
              parent_got_revision='1111111') + api.properties(
                  parent_build_archive_url='gs://test-domain/test-archive.zip'))