these 2 derivations will be built:
  /nix/store/1xaj976ppi5j4yg3a8n3v6p5f23q7sdf-resulting-skills-tree.drv
  /nix/store/7rmb6cf002sy2112h01hnirbk3baadn6-validate-skills.drv
warning: SQLite database '/nix/var/nix/db/db.sqlite' is busy