The test is good, but Jim forgot to check in the updated output.
diff --git a/Lib/test/output/test_StringIO b/Lib/test/output/test_StringIO
index ce983c0..e2c5c31 100644
--- a/Lib/test/output/test_StringIO
+++ b/Lib/test/output/test_StringIO
@@ -4,8 +4,14 @@
 
 2
 'abcdefghij'
+'abcde'
+Caught expected ValueError writing to closed StringIO:
+I/O operation on closed file
 abcdefghij
 klmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
 
 2
 'abcdefghij'
+'abcde'
+Caught expected ValueError writing to closed StringIO:
+I/O operation on closed file