[bisect] - Bail early when bisecting return codes.

tools/auto_bisect/bisect_perf_regression.py

 #!/usr/bin/env python
 # Copyright 2013 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.
 
 """Chromium auto-bisect tool
 
 This script bisects a range of commits using binary search. It starts by getting
 reference values for the specified "good" and "bad" commits. Then, for revisions
 in between, it will get builds, run tests and classify intermediate revisions as
@@ skipping 1346 matching lines @@
       if metric and self._IsBisectModeUsingMetric():
         parsed_metric = _ParseMetricValuesFromOutput(metric, output)
         if parsed_metric:
           metric_values.append(math_utils.Mean(parsed_metric))
         # If we're bisecting on a metric (ie, changes in the mean or
         # standard deviation) and no metric values are produced, bail out.
         if not metric_values:
           break
       elif self._IsBisectModeReturnCode():
         metric_values.append(return_code)
+        # If there's a failed test, we can bail out early.
+        if return_code:
+          break
 
       elapsed_minutes = (time.time() - start_time) / 60.0
       time_limit = self.opts.max_time_minutes * test_run_multiplier
       if elapsed_minutes >= time_limit:
         break
 
     if metric and len(metric_values) == 0:
       err_text = 'Metric %s was not found in the test output.' % metric
       # TODO(qyearsley): Consider also getting and displaying a list of metrics
       # that were found in the output here.
@@ skipping 1499 matching lines @@
       # bugs. If you change this, please update the perf dashboard as well.
       bisect_utils.OutputAnnotationStepStart('Results')
     print 'Runtime Error: %s' % e
     if opts.output_buildbot_annotations:
       bisect_utils.OutputAnnotationStepClosed()
   return 1
 
 
 if __name__ == '__main__':
   sys.exit(main())