Update metadata with a single patch call

rule.js

function(user, context, callback) {

  const request = require('request');
  const userApiUrl = auth0.baseUrl + '/users';

  function updateMetadata(cb) {
    console.log('updating');
    request.patch({
      url: userApiUrl + '/' + user.user_id,
      headers: {
        Authorization: 'Bearer ' + auth0.accessToken
      },
      json: {
        app_metadata: user.app_metadata,
        user_metadata: user.user_metadata
      }
    }, function(err, res, body) {
      if (err) {
        return cb(err);
      }
      if (res.statusCode >= 400) {
        return cb(new Error('Error updating metadata: ' + res.statusMessage));
      }
      return cb(null);
    });
  }
  
  user.user_metadata = {
    color: 'red'
  };
  
  let changed = true;
  
  if (changed) {
    return updateMetadata(function(err) {
      callback(err, user, context);
    });
  }

  callback(null, user, context);
 
}