Fix buglet in sliceobjects, they were not returning Py_NotImplemented when

compared against something other than sliceobjects.

Lib/test/test_slice.py

@@ -26,6 +26,9 @@ class SliceTest(unittest.TestCase):
         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

Objects/sliceobject.c

@@ -286,6 +286,11 @@ slice_richcompare(PyObject *v, PyObject *w, int op)
 	PyObject *t2;
 	PyObject *res;
 
+	if (!PySlice_Check(v) || !PySlice_Check(w)) {
+		Py_INCREF(Py_NotImplemented);
+		return Py_NotImplemented;
+	}
+
 	if (v == w) {
 		/* XXX Do we really need this shortcut?
 		   There's a unit test for it, but is that fair? */