these 2 derivations will be built:
  /nix/store/1qyda67ss63xv5vbzhfby8wi1a1rg4q1-harmonia-deps-3.3.0.drv
  /nix/store/v8gahvxkyrsnl5fba9qby8z5zvsgyyjg-harmonia-llvm-cov-3.3.0.drv