Fix a flaky gsubtreed test caused by git2.repo logging

infra/services/gsubtreed/test/gsubtreed_test.py

Index: infra/services/gsubtreed/test/gsubtreed_test.py
diff --git a/infra/services/gsubtreed/test/gsubtreed_test.py b/infra/services/gsubtreed/test/gsubtreed_test.py
index c65120fe697d57ac815a9e3001a759f0f02e81f7..b994eec8ecd843aa16a0aa8b00cd75e6ccc346ad 100644
--- a/infra/services/gsubtreed/test/gsubtreed_test.py
+++ b/infra/services/gsubtreed/test/gsubtreed_test.py
@@ -102,7 +102,12 @@ def RunTest(test_name):
       sys.stderr = stderr
 
       root_logger.removeHandler(shandler)
-      ret.append({'log output': logout.getvalue().splitlines()})
+
+      # infra.libs.git2.repo logs this message if the command took longer than
+      # 1s to run.  This causes test flakes occasionally.
+      log_lines = [x for x in logout.getvalue().splitlines()
+                   if 'Finished in ' not in x]
+      ret.append({'log output': log_lines})
 
       ret.append({
         'inner_loop success': success,