these 2 derivations will be built:
  /nix/store/aw978fxxaxijx15fm0v8s2jd2h83r1x7-nixos-test-driver-pgtap.drv
  /nix/store/dv50jcrf5kaasg1xrm77kvsmbn0463yh-vm-test-run-pgtap.drv