Transaction with Persistent

I'm using Persisent with a MySQL database and it seems transaction are not working.

I'm doing something similar to

runDB $ do
    insertMany something
    error "should rollback"
    insertMany somethingElse

I expect something to not be in the database. The call to error should rollback the transaction, but when I do it, something is inserted in the database. Am I missing something ? (I've checked that autocommit is set to 0, and it is).