https://github.com/TryGhost/Toolbox/issues/130
The transaction no longer commits in the promise chain, which wasn't
valid logic for a transaction, since it is commited automatically when
the promise chain resolves, and rollsback automatically when the
promise chain rejects.
This makes code which fails during the transaction error in the right
place, instead of getting stuck here. (Especially good for writing
tests).
The tests for this code can now live in the integration folder.
