these 3 derivations will be built:
  /nix/store/738fadfmvfnhcww7nvdvz1cpa97pxhn0-but-0.21.1-vendor-staging.drv
  /nix/store/ssir0vcsc6g18p0shs9cmwkia4kf3ipy-but-0.21.1-vendor.drv
  /nix/store/37bck8vcivdxxzbdh17bcg66nh846yxp-but-0.21.1.drv