Delivery 1 wrote no commit on the key of a pulled-in module, so after the upgrade those modules fell out of SentBuilds. At the start of the lease holder a copy fills every key that names no commit (creating a standing pulled-in key where none stands), overwrites nothing, empties each column it copied, and raises an urgent condition while it fails. Migration 0105 no longer drops node.sent_builds (issue 1112 does).
The migration raises first unless chain_moved names builds, rollouts and assignments for every kind that holds rows, and unless pending_assignment holds no open or unanswered row; then it drops build_request, build, batched_merge, release_plan, pending_assignment, assignment, raise_assignment_generation(), node.sent_builds and chain_moved. build_gate stays.