bpo-41100: in test_platform, ignore 10.16 (pythonGH-23485)

(cherry picked from commit c0c23ea)

Co-authored-by: Ned Deily <nad@python.org>

Lib/test/test_platform.py

@@ -237,7 +237,10 @@ def test_mac_ver(self):
             # On Snow Leopard, sw_vers reports 10.6.0 as 10.6
             if len_diff > 0:
                 expect_list.extend(['0'] * len_diff)
-            self.assertEqual(result_list, expect_list)
+            # For compatibility with older binaries, macOS 11.x may report
+            # itself as '10.16' rather than '11.x.y'.
+            if result_list != ['10', '16']:
+                self.assertEqual(result_list, expect_list)
 
             # res[1] claims to contain
             # (version, dev_stage, non_release_version)