structuredAttrs is enabled

trying https://github.com/github/spec-kit/archive/refs/tags/v1.0.12.tar.gz
  % Total    % Received % Xferd  Average Speed  Time    Time    Time   Current
                                 Dload  Upload  Total   Spent   Left   Speed

  0      0   0      0   0      0      0      0                              0
  0      0   0      0   0      0      0      0                              0
  0      0   0      0   0      0      0      0                              0

  0      0   0      0   0      0      0      0                              0
100  4.27M   0  4.27M   0      0  5.49M      0                              0
100  4.27M   0  4.27M   0      0  5.49M      0                              0
100  4.27M   0  4.27M   0      0  5.49M      0                              0
unpacking source archive /nix/var/nix/builds/nix-3970-1512341382/download.tar.gz