Possible testdouble.js regression?

error.js

'use strict';

// Much of this was inspired by sequelize's error module
// https://github.com/sequelize/sequelize/blob/master/lib/errors.js

var util = require('util');

var error = {};

// Every built in error inherits from this error
error.BaseError = function () {
  var tmp = Error.apply(this, arguments);
  tmp.name = this.name = 'BaseError';

  this.message = tmp.message;
  this.status = 500;
  Error.captureStackTrace(this, this.constructor);
};
util.inherits(error.BaseError, Error);

error.BaseError.prototype.toJSON = function () {
  return {
    type: this.name,
    message: this.message
  };
};


// used when the user cannot access something
error.AccessDeniedError = function (message) {
  error.BaseError.call(this, message);
  this.name = 'AccessDeniedError';
  this.status = 403;
};
util.inherits(error.AccessDeniedError, error.BaseError);


// Used when the user passes in invalid data
error.ValidationError = function (message, validations) {
  error.BaseError.call(this, message);
  this.name = 'ValidationError';
  this.status = 422;

  if (typeof validations === 'undefined') {
    validations = null;
  }
  this.validations = validations;
};
util.inherits(error.ValidationError, error.BaseError);

error.ValidationError.prototype.toJSON = function () {
  var json = error.BaseError.prototype.toJSON.call(this);

  json.validations = this.validations;

  return json;
};


module.exports = error;

test.js

'use strict';

var td = require('testdouble');
var error = td.replace('./error');

var ad = new error.AccessDeniedError('Whoops!');  // works in 1.9.1 and 1.10.0

// for me, in 1.10.0 this returns `error.ValidationError is not a constructor`
var vd = new error.ValidationError('Oh no!');  // only works in 1.9.1