Update Lib/test/test_io/test_bufferedio.py

Co-authored-by: sobolevn <mail@sobolevn.me>

Author: hyongtao-code

Lib/test/test_io/test_bufferedio.py

@@ -638,6 +638,7 @@ def test_read1_error_does_not_cause_reentrant_failure(self):
             with self.assertRaises(MemoryError):
                 bufio.read1(huge)
 
+            # Used to crash before gh-143689:
             self.assertEqual(bufio.read1(1), b"h")