these 2 derivations will be built:
  /nix/store/9b842v1ln4hvj20wchzij84pq555j3ky-resulting-skills-tree.drv
  /nix/store/w9qljlrs5cyjdlmwccx08hahd4b6kfyf-validate-skills.drv
warning: SQLite database '/nix/var/nix/db/db.sqlite' is busy