Moving AutoBisectApi.working_dir fallback logic to the property code.

scripts/slave/recipe_modules/auto_bisect/api.py

 # Copyright 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.
 
 """API for the bisect recipe module.
 
 This API is meant to enable the bisect recipe to bisect any chromium-supported
 platform for any test that can be run via buildbot, perf or otherwise.
 """
 
@@ skipping 37 matching lines @@
     self.full_deploy_script = None
 
     # Keep track of working directory (which contains the checkout).
     # None means "default value".
     self._working_dir = None
 
   @property
   def working_dir(self):
    if not self._working_dir:
      self._working_dir = self.m.chromium_tests.get_checkout_dir({})
-   return self._working_dir
+   return self._working_dir or self.m.path['slave_build']
 
   def perform_bisect(self, **flags):
     return local_bisect.perform_bisect(self, **flags)
 
   def create_bisector(self, bisect_config_dict, dummy_mode=False, **flags):
     """Passes the api and the config dictionary to the Bisector constructor.
 
     For details about the keys in the bisect config dictionary go to:
     http://chromium.org/developers/speed-infra/perf-try-bots-bisect-bots/config
 
@@ skipping 342 matching lines @@
               affected_files, update_step, self.bot_db)
       finally:
         if api.chromium.c.TARGET_PLATFORM == 'android':
           if self.internal_bisect:  # pragma: no cover
             api.chromium_android.init_and_sync(
                 gclient_config=api.chromium_android.c.internal_dir_name,
                 use_bot_update=True)
           else:
             self.ensure_checkout()
           api.chromium_android.common_tests_final_steps()