these 3 derivations will be built:
  /nix/store/w6v028d2qvpfpr5w1wr7rapyc3b3w3bm-source.drv
  /nix/store/qr8mw793zmyzanyxsazg2a6lqd39x451-harmonia-deps-3.3.0.drv
  /nix/store/rvkkwrfw1gyjwhqxb9f6d64y4b9iy636-harmonia-llvm-cov-3.3.0.drv