Shutdown multiprocess pool after running tests to avoid _finalizer spew on Windows

presubmit_support.py

Index: presubmit_support.py
diff --git a/presubmit_support.py b/presubmit_support.py
index 5851178f11cc619791e7ab8c6f0d48e8495ce4cc..342388e64ae5d34e4983b70127a4ae17270047c1 100755
--- a/presubmit_support.py
+++ b/presubmit_support.py
@@ -563,6 +563,11 @@ class InputApi(object):
       msgs.extend(map(CallCommand, tests))
     return [m for m in msgs if m]
 
+  def ShutdownPool(self):
+    self._run_tests_pool.close()
+    self._run_tests_pool.join()
+    self._run_tests_pool = None
+
 
 class _DiffCache(object):
   """Caches diffs retrieved from a particular SCM."""
@@ -1448,6 +1453,8 @@ class PresubmitExecuter(object):
     else:
       result = ()  # no error since the script doesn't care about current event.
 
+    input_api.ShutdownPool()
+
     # Return the process to the original working directory.
     os.chdir(main_path)
     return result