Protect against attempts to replace PyNumber_Add with PyNumber_InPlaceAdd in builtin sum

diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 05556169b7dfecf50d771bd0007be0dd9ad55872..3cd5bd955f1627f8ae3c8793ccd31123b9723649 100644 (file)
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -1286,6 +1286,10 @@ class BuiltinTest(unittest.TestCase):
                 raise ValueError
         self.assertRaises(ValueError, sum, BadSeq())
 
+        empty = []
+        sum(([x] for x in range(10)), empty)
+        self.assertEqual(empty, [])
+
     def test_type(self):
         self.assertEqual(type(''),  type('123'))
         self.assertNotEqual(type(''), type(()))