Running nix-build under strace?

I’m trying to debug an package upgrade, and the package is hitting a permission error when trying to configure itself

    File "/nix/store/ygyc255lpn43cy737kmr7a5g81g46nxw-python3.8-setuptools-50.3.1/lib/python3.8/site-packages/setuptools/", line 145, in run_setup
      exec(compile(code, __file__, 'exec'), locals())
    File "", line 70, in <module>
    File "/nix/store/2wwprmwlgyx443lkdwx4spv0gj9fh274-python3.8-extension-helpers-0.1/lib/python3.8/site-packages/extension_helpers/", line 82, in get_extensions
      shutil.copy(os.path.join(src_path, 'compiler.c'),
    File "/nix/store/m7080pw0ryjk0jhljp55rq1hd2qy8gki-python3-3.8.6/lib/python3.8/", line 415, in copy
      copyfile(src, dst, follow_symlinks=follow_symlinks)
    File "/nix/store/m7080pw0ryjk0jhljp55rq1hd2qy8gki-python3-3.8.6/lib/python3.8/", line 261, in copyfile
      with open(src, 'rb') as fsrc, open(dst, 'wb') as fdst:
  PermissionError: [Errno 13] Permission denied: './astropy/_compiler.c'

I’d like to run the nix-build under strace so I can see exactly what it’s doing. Does anyone know how to do that? It seems like strace nix-build ... doesn’t actually strace the builder script.