these 2 derivations will be built:
  /nix/store/0dhkk09hjx3qx0c3q10da81f4nhjgcn5-harmonia-deps-3.1.0.drv
  /nix/store/0sid9aym7crnx3ck1i60p38mmmiv9pz2-harmonia-llvm-cov-3.1.0.drv