buildbucket: support unique change urls

scripts/master/buildbucket/unittests/changestore_test.py

Index: scripts/master/buildbucket/unittests/changestore_test.py
diff --git a/scripts/master/buildbucket/unittests/changestore_test.py b/scripts/master/buildbucket/unittests/changestore_test.py
index 338689817cf2b0495245fa3b579c678a1cbe3a69..f6782aa2e22ab9cc291a7f3dcc033896562621b8 100755
--- a/scripts/master/buildbucket/unittests/changestore_test.py
+++ b/scripts/master/buildbucket/unittests/changestore_test.py
@@ -70,9 +70,9 @@ class ChangeStoreTest(unittest.TestCase):
     cache.get.return_value = None
     result = run_deferred(self.store.get_change(self.buildbucket_change))
 
-    info = json.dumps({
+    info = {
         common.BUILDBUCKET_CHANGE_ID_PROPERTY: '1',
-    }, sort_keys=True)
+    }
     self.buildbot.add_change_to_db.assert_called_once_with(
         author=self.buildbucket_change['author']['email'],
         files=[],
@@ -100,7 +100,7 @@ class ChangeStoreTest(unittest.TestCase):
         'message': 'Hello world',
     }))
 
-    expected_info = json.dumps({'change_id': None})
+    expected_info = {'change_id': None}
     self.buildbot.add_change_to_db.assert_called_once_with(
         author='johndoe@chromium.org',
         files=[],