structuredAttrs is enabled

trying https://beta.quicklisp.org/archive/nyaml/2025-06-22/nyaml-20250622-git.tgz
  % Total    % Received % Xferd  Average Speed  Time    Time    Time   Current
                                 Dload  Upload  Total   Spent   Left   Speed

  0      0   0      0   0      0      0      0                              0
100 165.3k 100 165.3k   0      0  1.45M      0                              0
100 165.3k 100 165.3k   0      0  1.45M      0                              0
100 165.3k 100 165.3k   0      0  1.45M      0                              0
unpacking source archive /nix/var/nix/builds/nix-75674-1774452284/nyaml-20250622-git.tgz