structuredAttrs is enabled

trying https://github.com/yvgude/lean-ctx/archive/refs/tags/v3.9.18.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
100 13.06M   0 13.06M   0      0  9.03M      0           00:01         10.71M
unpacking source archive /nix/var/nix/builds/nix-95255-3806270042/download.tar.gz