these 2 derivations will be built:
  /nix/store/n5vqcbwvizbcxih82lsmybz21m1l6yz3-nixos-test-driver-pg_repack.drv
  /nix/store/zhfwyrlb4sjdajh9cbvplw4d5kc814cy-vm-test-run-pg_repack.drv