these 2 derivations will be built:
  /nix/store/myz95jhlcgikqhkivffnzg3gjss82pdi-harmonia-deps-3.1.0.drv
  /nix/store/ins7bb7l7y6wwhgx8lmx87chzh40a21a-harmonia-llvm-cov-3.1.0.drv