transaction: turn lack of locking into a hard failure (API) We have been warning about transactions without locks for about a year (and three releases), third party extensions had a fair grace period to fix their code, we are moving lack of locking to a hard failure in order to protect users against repository corruption.

test: extract develwarn transaction testing in its own command The lack of locking for a transation is about to change from a warning to an error. We first extract the test decidated to this warning to make the next changeset clearer.