structuredAttrs is enabled

trying https://github.com/jthomperoo/simple-proxy/archive/v1.4.0.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  11616   0  11616   0      0  20318      0                              0
100  11616   0  11616   0      0  20314      0                              0
100  11616   0  11616   0      0  20310      0                              0
unpacking source archive /nix/var/nix/builds/nix-15688-1250836430/download.tar.gz