test that -X traceback_timestamps goes to spawned pythons

Author: gpshead

Lib/test/test_support.py

@@ -573,6 +573,8 @@ def test_args_from_interpreter_flags(self):
             ['-X', 'importtime'],
             ['-X', 'importtime=2'],
             ['-X', 'showrefcount'],
+            ['-X', 'traceback_timestamps'],
+            ['-X', 'traceback_timestamps=ns'],
             ['-X', 'tracemalloc'],
             ['-X', 'tracemalloc=3'],
         ):