these 4 derivations will be built:
  /nix/store/i030bzibd3w9gjp6vv9287pbm2kad81x-source.drv
  /nix/store/6af9d9k1avd8yr5gwfi5rch8r90zka8w-but-0.21.1-vendor-staging.drv
  /nix/store/w4z3frv4145nwxlrrbdwndb1gzzzzx5s-but-0.21.1-vendor.drv
  /nix/store/hhzjyvvmgidgckk9pr6sw0a490j54w5x-but-0.21.1.drv