message: Add back check for string 'undefined'
  (There was probably some case where this was happening instead of the 'null' thing)
diff: @@ -11,7 +11,7 @@ module.exports = function retrieveBasket () {
  /* jshint eqeqeq:false */
  if (utils.notSolved(challenges.basketAccessChallenge)) {
  const user = insecurity.authenticatedUsers.from(req)
  - if (user && id && id !== 'null' && user.bid != id) { // eslint-disable-line eqeqeq
  + if (user && id && id !== 'undefined' && id !== 'null' && user.bid != id) { // eslint-disable-line eqeqeq
  utils.solve(challenges.basketAccessChallenge)
  }
  }
  