I haven't had a time to investigate this yet, but I don't think there is an issue with SQLite itself.

Note that pysqlite behaves the same way since version 2.8.0 and I couldn't find a similar report in their issue tracker.

Like Serhiy, I'm also a little puzzled with the reproducer. I think if you want to start an explicit transaction, the preferred way would be to set isolation_level to None. Otherwise, the sqlite3 module will start one implicitly for you (or perhaps I still don't understand PEP 249's transaction model 100% correctly :))

(If we decide that this is not a regression, we should add a test case to cover this use case.)