Incorrect emit when using external module import in JSX tag

[RyanCavanaugh]

From @prabirshrestha (thanks!) at #3564 (comment)

---

Tried building tsc locally and running this.

jake LKG
node ..\bin\tsc.js --jsx react -m umd -t es5 app.tsx button.tsx

app.tsx:

/// <references file="./react.d.ts"/>

import * as React from 'react';

import { Button } from './button';

export class App extends React.Component<any, any> {

    render() {
        return <Button />;
    }

}

button.tsx

import * as React from 'react';

export class Button extends React.Component<any, any> {

    render() {
        return <button>Some button</button>;
    }

}

The output app.js does not seem to set the button as a dependency.

/// <references file="./react.d.ts"/>
var __extends = (this && this.__extends) || function (d, b) {
    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
    function __() { this.constructor = d; }
    d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
(function (deps, factory) {
    if (typeof module === 'object' && typeof module.exports === 'object') {
        var v = factory(require, exports); if (v !== undefined) module.exports = v;
    }
    else if (typeof define === 'function' && define.amd) {
        define(deps, factory);
    }
})(["require", "exports", 'react'], function (require, exports) {
    var React = require('react');
    var App = (function (_super) {
        __extends(App, _super);
        function App() {
            _super.apply(this, arguments);
        }
        App.prototype.render = function () {
            return React.createElement(button_1.Button, null);
        };
        return App;
    })(React.Component);
    exports.App = App;
});

This makes button_1 undefined. Even with -m amd it doesn't seem to work. Am I missing something here or is this a bug?