this derivation will be built:
  /nix/store/7kh0sknw9ffrla80xvz36d6ygzjfmw29-fail-4.drv
building '/nix/store/7kh0sknw9ffrla80xvz36d6ygzjfmw29-fail-4.drv'
fail-4> tribuchet: building on jamie
fail-4> this build is supposed to fail
error: Cannot build '/nix/store/7kh0sknw9ffrla80xvz36d6ygzjfmw29-fail-4.drv'.
       Reason: builder failed with exit code 1.
       Output paths:
         /nix/store/ziwm9bqr7cgqkbl3z4zpjx4kxivc7mr6-fail-4
       Last 2 log lines:
       > tribuchet: building on jamie
       > this build is supposed to fail
       For full logs, run:
         nix log /nix/store/7kh0sknw9ffrla80xvz36d6ygzjfmw29-fail-4.drv