these 3 derivations will be built:
  /nix/store/1szcz7zv0zi70vsak0gmpjgg7zmzhxhl-source.drv
  /nix/store/byzdc4cl2db9z5092vvlmfihmsg8f07y-parallel-cli-0.9.4.drv
  /nix/store/fpvpa1n8dqpny5zg6zkn8ldrf672papr-check-parallel-cli.drv
warning: SQLite database '/nix/var/nix/db/db.sqlite' is busy