Try to make test_threaded_import faster and safer (issue #15599).
diff --git a/Lib/test/test_threaded_import.py b/Lib/test/test_threaded_import.py
index 93bfb2a..e0c23de 100644
--- a/Lib/test/test_threaded_import.py
+++ b/Lib/test/test_threaded_import.py
@@ -72,7 +72,7 @@
         with self.lock:
             self.numcalls += 1
         x = self.x
-        time.sleep(0.1)
+        time.sleep(0.01)
         self.x = x + 1
 
 class FlushingFinder:
@@ -117,7 +117,7 @@
                 t = threading.Thread(target=task,
                                      args=(N, done, done_tasks, errors,))
                 t.start()
-            done.wait(60)
+            self.assertTrue(done.wait(60))
             self.assertFalse(errors)
             if verbose:
                 print("OK.")