PyPy/Win is flaky. Cant reproduce on any other PyPy

docs/changes/1698.bugfix

@@ -2,7 +2,8 @@ Improve the ability to use monkey-patched locks, and
 `gevent.lock.BoundedSemaphore`, across threads, especially when the
 various threads might not have a gevent hub or any other active
 greenlets. In particular, this handles some cases that previously
-raised ``LoopExit`` or would hang.
+raised ``LoopExit`` or would hang. Note that this may not be reliable
+on PyPy on Windows; such an environment is not currently recommended.
 
 The semaphore tries to avoid creating a hub if it seems unnecessary,
 automatically creating one in the single-threaded case when it would

src/gevent/testing/__init__.py

@@ -93,6 +93,7 @@ from .skipping import skipOnCI
 from .skipping import skipOnPyPy3OnCI
 from .skipping import skipOnPyPy
 from .skipping import skipOnPyPyOnCI
+from .skipping import skipOnPyPyOnWindows
 from .skipping import skipOnPyPy3
 from .skipping import skipIf
 from .skipping import skipUnless

src/gevent/tests/test__semaphore.py

@@ -238,6 +238,7 @@ class TestSemaphoreMultiThread(greentest.TestCase):
     def assertOneHasNoHub(self, sem):
         self.assertIsNone(sem.hub, sem)
 
+    @greentest.skipOnPyPyOnWindows("Flaky there; can't reproduce elsewhere")
     def test_dueling_threads(self, acquire_args=(), create_hub=None):
         # pylint:disable=too-many-locals,too-many-statements