Merge branch 'regen'

* regen:
  v2writable: use msgmap as multi_mid queue
  v2writable: move git->cleanup to the correct place
  v2writable: reindex handles 3-headered monsters
  v2writable: improve "num_for" API and disambiguate
  v2writable: set unindexed article number

diff --cc TODO
Simple merge

diff --cc lib/PublicInbox/OverIdx.pm
Simple merge