gh-130250: fix cleanup in test (impacts refleaks runs) (#130329)

diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index 58f28902686a17cd601afc24bea02297332ec1bb..266a1ec04908fc203003712c3ef8f15c734b42e4 100644 (file)
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -512,10 +512,13 @@ class TracebackCases(unittest.TestCase):
 
     def test_print_last(self):
         self.assertIsNone(getattr(sys, "last_exc", None))
-        sys.last_exc = ValueError(42)
-        output = StringIO()
-        traceback.print_last(file=output)
-        self.assertEqual(output.getvalue(), "ValueError: 42\n")
+        try:
+            sys.last_exc = ValueError(42)
+            output = StringIO()
+            traceback.print_last(file=output)
+            self.assertEqual(output.getvalue(), "ValueError: 42\n")
+        finally:
+            sys.last_exc = None
 
     def test_format_exception_exc(self):
         e = Exception("projector")