asyncio: Fix granularity of test_utils.TestLoop.
diff --git a/Lib/asyncio/test_utils.py b/Lib/asyncio/test_utils.py
index 42b9cd7..fed28d7 100644
--- a/Lib/asyncio/test_utils.py
+++ b/Lib/asyncio/test_utils.py
@@ -196,6 +196,7 @@
         next(self._gen)
         self._time = 0
         self._timers = []
+        self._granularity = 1e-9
         self._selector = TestSelector()
 
         self.readers = {}