Setting --run-python-script flag for runtest.py invocation.

scripts/slave/recipe_modules/bisect_tester/perf_test.py

Index: scripts/slave/recipe_modules/bisect_tester/perf_test.py
diff --git a/scripts/slave/recipe_modules/bisect_tester/perf_test.py b/scripts/slave/recipe_modules/bisect_tester/perf_test.py
index 0c6f3147070eea41641f50a997cf0935d8a0308c..66d742739d64968f280fed19eb20b62f80306667 100644
--- a/scripts/slave/recipe_modules/bisect_tester/perf_test.py
+++ b/scripts/slave/recipe_modules/bisect_tester/perf_test.py
@@ -199,12 +199,27 @@ def _run_command(api, command, step_name):
   if 'android-chrome' in command:  # pragma: no cover
     kwargs['env'] = {'CHROMIUM_OUTPUT_DIR': api.m.chromium.output_dir}
 
+  # By default, we assume that the test to run is an executable binary. In the
+  # case of python scripts, runtest.py will guess based on the extension.
+  python_mode = False
+  if command_parts[0] == 'python':  # pragma: no cover
+    # Dashboard prepends the command with 'python' when on windows, however, it
+    # is not necessary to pass this along to the runtest.py invocation.
+    # TODO(robertocn): Remove this clause when dashboard stops sending python as
+    # part of the command.

[sullivan, 2016/04/25 19:25:04]

One final nit: Please file a dashboard bug and link it here.

Also, I just realized: when it's fixed on the dashboard side, how will the
bisect know to set python_mode=True here?

[RobertoCN, 2016/04/25 19:34:31]

Done.

[RobertoCN, 2016/04/25 19:34:31]

It will go into the if _is_telemetry_command(...) like it does for mac and linux
where we also set it to True. (And note that this is only necessary because
there's no '.py' extension on the command, otherwise runtest.py would infer it
correctly)

+    command_parts = command_parts[1:]
+    python_mode = True
+  elif _is_telemetry_command(command):
+    # run_benchmark is a python script without an extension, hence we force
+    # python mode.
+    python_mode = True
   try:
     step_result = api.m.chromium.runtest(
         test=_rebase_path(command_parts[0]),
         args=command_parts[1:],
         xvfb=True,
         name=step_name,
+        python_mode=python_mode,
         stdout=stdout,
         stderr=stderr,
         **kwargs)