Comment 1 for bug 1701260

this is not inherently a bug in oslo.db. this has to do when specific failure conditions occur within MySQL, and then SQLAlchemy's attempt to "autorollback" the transaction also fail. However, "autorollback" shouldn't be happening here because it means the ORM Session is being used in autocommit mode without a transaction, which is strongly recommended against and would not occur if oslo.db's usual enginefacade system were being used.