these 3 derivations will be built:
  /nix/store/0y30qsg7ll0r51k7hrfynf4jm91cxac6-source.drv
  /nix/store/bn91kri3rlcsli4ik9vl0vhb1b0xqm73-harmonia-deps-3.2.0.drv
  /nix/store/qs2b8y3a7nhxlszaci41ihm9prwz1v6p-harmonia-llvm-cov-3.2.0.drv