these 6 derivations will be built:
  /nix/store/z3x1d9rxlqrx7rqw07456y7d4hw4nw28-nixos-system-server-test.drv
  /nix/store/3iv7gcjb1v73ypwnnkan3dgnx76ij13f-closure-info.drv
  /nix/store/fq5hicg7lr0x91a94w7hx7gwz0r763s3-run-nixos-vm.drv
  /nix/store/a92yv58py2q1jypasixkwyfxqcsc2sxc-nixos-vm.drv
  /nix/store/d4jfapcrb89ymsrpjc5pfl3vpd29fgh6-nixos-test-driver-pg_repack.drv
  /nix/store/40qbxnakqgnabb5cy0agk4fp2w3fsxbr-vm-test-run-pg_repack.drv