Make blink_trybot recipe work on windows

scripts/slave/unittests/recipes_test.py

Index: scripts/slave/unittests/recipes_test.py
diff --git a/scripts/slave/unittests/recipes_test.py b/scripts/slave/unittests/recipes_test.py
index 19bd064ea68d32ee9620d752d06bfafa77acae26..ddc4b6e40e388a0112c1d8e32a54a3fa8f96537b 100755
--- a/scripts/slave/unittests/recipes_test.py
+++ b/scripts/slave/unittests/recipes_test.py
@@ -41,7 +41,6 @@ import contextlib
 import json
 import os
 import sys
-import unittest
 
 from glob import glob
 
@@ -49,6 +48,9 @@ import test_env  # pylint: disable=W0611
 
 import coverage
 
+import common.python26_polyfill  # pylint: disable=W0611
+import unittest
+
 from common import annotator
 
 SCRIPT_PATH = os.path.abspath(os.path.dirname(__file__))
@@ -198,7 +200,7 @@ def train_from_tests(recipe_path):
     steps = execute_test_case(test_data, recipe_path)
     expected_path = expected_for(recipe_path, name)
     print 'Writing', expected_path
-    with open(expected_path, 'w') as f:
+    with open(expected_path, 'wb') as f:
       f.write('[')
       first = True
       for step in steps:
@@ -228,7 +230,7 @@ def load_tests(loader, _standard_tests, _pattern):
               steps = execute_test_case(test_data, recipe_path)
               # Roundtrip json to get same string encoding as load
               steps = json.loads(json.dumps(steps))
-              with open(expected_path, 'r') as f:
+              with open(expected_path, 'rb') as f:
                 expected = json.load(f)
               self.assertEqual(steps, expected)
             test_.__name__ += name