-- A build says what it was made from, as files (novox/hq ADR 0267, issue 363).
--
-- A merge to a repository moved every module whose build read it, whatever the files: the controller,
-- built from its repository's root, and the two images whose context is that repository (issue 338).
-- A build of a trunk commit now says its build source per repository — a Go program's import closure,
-- an archive's directory, an image's recipe — and the planner maps the next merge's changed files onto
-- the build source of the module's newest build. Null for a build that said none (one off the trunk,
-- one from a builder that predates this, one whose source is not known): its module is read as before.
alter table build add column build_sources jsonb;