these 3 derivations will be built:
  /nix/store/z4q56m5gn6wm2sbkla6aac01hbacmlps-source.drv
  /nix/store/6w22bybh1gq1n2ahssnlmm8649x06sz7-harmonia-deps-3.3.0.drv
  /nix/store/zqllfl7xkvaim50p5wppm659y9lgshgz-harmonia-llvm-cov-3.3.0.drv