test__pool.py: do not do kill(block=True) since blocking is default

--HG--
extra : transplant_source : V%93%89%10%AAx%7D%5C%85%CDn%CDeB%B5%80U%C8p%C2

greentest/test__pool.py

@@ -246,7 +246,7 @@ class TestPool(greentest.TestCase):
     def test_terminate(self):
         result = self.pool.map_async(gevent.sleep, [0.1] * 1000)
         kill = TimingWrapper(self.pool.kill)
-        kill(block=True)
+        kill()
         assert kill.elapsed < 0.5, kill.elapsed