Installing ReactTestRenderer@15.4.0-rc.1 from npm just brings down an index.js file, the referenced lib folder does not exist.

var done = this.async();
  var spawnCmd = {
    cmd: 'npm',
    args: ['pack', 'packages/react-test-renderer'],
  };
  grunt.util.spawn(spawnCmd, function() {
    var buildSrc = 'react-test-renderer-' + grunt.config.data.pkg.version + '.tgz';
    var buildDest = 'build/packages/react-test-renderer.tgz';
    fs.rename(buildSrc, buildDest, done);
  });
}
module.exports = {
  buildRelease: buildRelease,
  packRelease: packRelease,
};