Put in patch with a print statement to trace execution.
I changed demo to use sqlite and navigated to:

 http://localhost:9017/demo/issue2147483647

reported that there was no such id, print statement did not trigger.

 http://localhost:9017/demo/issue2147483648

reported that there was no such id and the print statement
within the max id patch in rdbms_common.py was printed.

 http://localhost:9017/demo/issue2147483649

reported that there was no such id and the print statement
again was triggered to prove the patch was triggering.

Committed on: 2b551b6b0830 without the debugging print statement.

This obsoletes:

https://hg.python.org/tracker/roundup/rev/eb3be57f1ef2 and
https://hg.python.org/tracker/roundup/rev/1548763e8273

Closing.