Remove ignored bot_update "force" parameter.

scripts/slave/recipe_modules/perf_try/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 perf try job recipe module.
 
 This API is meant to enable the perf try job recipe on any chromium-supported
 platform for any test that can be run via buildbot, perf or otherwise.
 """
 
@@ skipping 150 matching lines @@
         modified_benchmarks.append(benchmark)
     return modified_benchmarks
 
   def _checkout_revision(self, update_step, bot_db, revision=None):
     """Checkouts specific revisions and updates bot_update step."""
     if revision:
       if self.m.platform.is_win:  # pragma: no cover
         self.m.chromium.taskkill()
       self.m.gclient.c.revisions['src'] = str(revision)
       update_step = self.m.bot_update.ensure_checkout(
-          suffix=str(revision), force=True, patch=False,
-          update_presentation=False)
+          suffix=str(revision), patch=False, update_presentation=False)
       assert update_step.json.output['did_run']
       self.m.chromium.runhooks(name='runhooks on %s' % str(revision))
 
     return update_step
 
   def _run_test(self, cfg, **kwargs):
     """Runs test from config and return results."""
     values, overall_output, retcodes = self.m.bisect_tester.run_test(
         cfg, **kwargs)
     all_values = self.m.bisect_tester.digest_run_results(values, retcodes, cfg)
@@ skipping 323 matching lines @@
 
 def _prepend_src_to_path_in_command(test_cfg):
   command_to_run = []
   for v in test_cfg.get('command').split():
     if v in ['./tools/perf/run_benchmark',
              'tools/perf/run_benchmark',
              'tools\\perf\\run_benchmark']:
       v = 'src/tools/perf/run_benchmark'
     command_to_run.append(v)
   test_cfg.update({'command': ' '.join(command_to_run)})