Revert "Merge pull request #186 from bitzesty/remove-transaction-rollback"
Revert "Merge pull request #186 from bitzesty/remove-transaction-rollback"

This reverts commit 7da2f97c861296a6e12019d6dcb3ed9b9be273b7, reversing
changes made to b3d3070dff7664d851a83bf0f632a50a34f8c7ff.

bitzesty/trade-tariff-backend,leftees/trade-tariff-backend,bitzesty/trade-tariff-backend,alphagov/trade-tariff-backend,leftees/trade-tariff-backend,leftees/trade-tariff-backend,alphagov/trade-tariff-backend,bitzesty/trade-tariff-backend,alphagov/trade-tariff-backend