these 4 derivations will be built:
  /nix/store/2p313kd6gdy3f1bkmv1yr3vbjr6jnnvc-source.drv
  /nix/store/hddkprrdizd5jw937f34gj1nsbgskfqi-but-0.21.2-vendor-staging.drv
  /nix/store/gjzskh6iam9m3kj8anxrhlzbp6h62h44-but-0.21.2-vendor.drv
  /nix/store/7100qjw92d3f9i46g4jf27x8laxfb9js-but-0.21.2.drv