this derivation will be built:
  /nix/store/0pvj79wxibsarshi1p4vwdf4f14xnmcb-treefmt-check.drv
error: Cannot build '/nix/store/0pvj79wxibsarshi1p4vwdf4f14xnmcb-treefmt-check.drv'.
       Reason: builder failed with exit code 1.
       Output paths:
         /nix/store/grcdqrfql6bf8ygvah66zi42gzkaf1wk-treefmt-check
       Last 25 log lines:
       > +            "missing top-level check: {expr}"
       > +        );
       > +        assert!(
       > +            expr.contains("f ? packages"),
       > +            "missing packages branch: {expr}"
       > +        );
       >          assert!(
       >              expr.contains("f ? legacyPackages"),
       >              "missing legacyPackages branch: {expr}"
       >          );
       > -        assert!(expr.contains("builtins.currentSystem"), "missing system: {expr}");
       > +        assert!(
       > +            expr.contains("builtins.currentSystem"),
       > +            "missing system: {expr}"
       > +        );
       >      }
       >
       >      #[test]
       >      fn build_flake_expression_dotted_attr_is_verbatim() {
       > -        let expr = build_flake_expression("/nix/store/x", "sha256-abc", "packages.x86_64-linux.samba");
       > +        let expr =
       > +            build_flake_expression("/nix/store/x", "sha256-abc", "packages.x86_64-linux.samba");
       >          // Fully-qualified path must be embedded verbatim; no resolution wrapper.
       >          assert!(
       >              expr.contains("packages.x86_64-linux.samba"),
       For full logs, run:
         nix log /nix/store/0pvj79wxibsarshi1p4vwdf4f14xnmcb-treefmt-check.drv