Update Lib/test/test_exceptions.py

Co-authored-by: Peter Bierma <[email protected]>

Author: yihong0618

Lib/test/test_exceptions.py

@@ -1920,6 +1920,13 @@ def test_keyerror_context(self):
     @unittest.skipIf(support.Py_TRACE_REFS, 'cannot test Py_TRACE_REFS build')
     def test_exec_set_nomemory_hang(self):
         import_module("_testcapi")
+        # gh-134163: A MemoryError inside code that was wrapped by a try/except
+        # block would lead to an infinite loop.
+
+        # The frame_lasti needs to be greater than 257 to prevent
+        # PyLong_FromLong() from returning cached integers, which
+        # don't require a memory allocation. Prepend some dummy code
+        # to artificially increase the instruction index.
         warmup_code = "a = list(range(0, 1))\n" * 20
         user_input = warmup_code + dedent("""
             try: