these 3 derivations will be built:
  /nix/store/n1dxm0nb982cyjwmf1f30hr5c9bdmxlh-source.drv
  /nix/store/dacc3hdnvnr4hc3w4p5qsizz198mnczx-harmonia-deps-3.3.0.drv
  /nix/store/vjii3l4h632ly6qfcz59lrj3w6nynvx3-harmonia-llvm-cov-3.3.0.drv