Brings the database up to head. Concurrent instances may run this at once;
that is safe because every revision is idempotent by construction, so
concurrent runs converge to the same state and the ledger records each
revision once. Idempotent — a no-op when nothing is pending. Returns the
revision ids applied this run and the declared head.
Brings the database up to head. Concurrent instances may run this at once; that is safe because every revision is idempotent by construction, so concurrent runs converge to the same state and the ledger records each revision once. Idempotent — a no-op when nothing is pending. Returns the revision ids applied this run and the declared head.