Fix buglet in sliceobjects, they were not returning Py_NotImplemented when
compared against something other than sliceobjects.
diff --git a/Lib/test/test_slice.py b/Lib/test/test_slice.py
index 4d89aa6..97b3084 100644
--- a/Lib/test/test_slice.py
+++ b/Lib/test/test_slice.py
@@ -26,6 +26,9 @@
         s3 = slice(1, 2, 4)
         self.assertEqual(s1, s2)
         self.assertNotEqual(s1, s3)
+        self.assertNotEqual(s1, None)
+        self.assertNotEqual(s1, (1, 2, 3))
+        self.assertNotEqual(s1, "")
 
         class Exc(Exception):
             pass