V8: Log captured MB output in case of failure

scripts/slave/recipe_modules/v8/api.py

 # 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.
 
 import argparse
 import contextlib
 import datetime
 import difflib
 import random
 import re
@@ skipping 438 matching lines @@
       use_goma = (self.m.chromium.c.compile_py.compiler and
                   'goma' in self.m.chromium.c.compile_py.compiler)
       def step_test_data():
         # Fake gyp flags.
         # TODO(machenbach): Replace with gn args after the gn migration.
         return self.m.raw_io.test_api.stream_output(
             'some line\n'
             'GYP_DEFINES=\'target_arch=x64 cool_flag=a=1\'\n'
             'moar\n'
         )
-      self.m.chromium.run_mb(
-          self.m.properties['mastername'],
-          self.m.properties['buildername'],
-          use_goma=use_goma,
-          mb_config_path=self.m.path['checkout'].join(
-              'infra', 'mb', 'mb_config.pyl'),
-          gyp_script=self.m.path.join('gypfiles', 'gyp_v8'),
-          stdout=self.m.raw_io.output(),
-          step_test_data=step_test_data,
-      )
-      # Log captured output.
-      self.m.step.active_result.presentation.logs['stdout'] = (
-        self.m.step.active_result.stdout.splitlines())
+      try:
+        self.m.chromium.run_mb(
+            self.m.properties['mastername'],
+            self.m.properties['buildername'],
+            use_goma=use_goma,
+            mb_config_path=self.m.path['checkout'].join(
+                'infra', 'mb', 'mb_config.pyl'),
+            gyp_script=self.m.path.join('gypfiles', 'gyp_v8'),
+            stdout=self.m.raw_io.output(),
+            step_test_data=step_test_data,
+        )
+      finally:
+        # Log captured output.
+        self.m.step.active_result.presentation.logs['stdout'] = (
+          self.m.step.active_result.stdout.splitlines())
 
       # Update the build environment dictionary, which is printed to the
       # user on test failures for easier build reproduction.
       self._update_build_environment(self.m.step.active_result.stdout)
 
     self.peek_gn()
     self.m.chromium.compile(**kwargs)
     self.isolate_tests()
 
   # TODO(machenbach): This should move to a dynamorio module as soon as one
@@ skipping 753 matching lines @@
   def report_culprits(self, culprit_range):
     assert culprit_range
     if len(culprit_range) > 1:
       text = 'Suspecting multiple commits'
     else:
       text = 'Suspecting %s' % culprit_range[0][:8]
 
     step_result = self.m.step(text, cmd=None)
     for culprit in culprit_range:
       step_result.presentation.links[culprit[:8]] = COMMIT_TEMPLATE % culprit