these 4 derivations will be built:
  /nix/store/l05hrpdzgvbfvn2zwnf8xwwck5w31i5y-source.drv
  /nix/store/ididx9ic1qq8b7l05043ajsvzvvnvqjd-omp-18.2.4-cargo-vendor-vendor-staging.drv
  /nix/store/sf9hkr43qw79zl7mnji31ifphii6rhsq-omp-18.2.4-cargo-vendor-vendor.drv
  /nix/store/nyky72vnqkpa4yxym9yy9hrbqi7qyxlc-omp-18.2.4.drv