title: Webpack (4) hot module reloading fetches update manifest from malformed URI
body: <p>When Webpack attempts to fetch the update JSON file, it fails with the console error message:</p>
  
  <pre><code>[HMR] Update failed: Error: Manifest request to https://subdomain.localhost23dae8e1865781c26fcd.hot-update.json timed out.
  </code></pre>
  
  <p>Note the omission of a slash between the TLD and the path…</p>
  
  <p><strong>Devserver config:</strong></p>
  
  <pre><code>{
    public: `subdomain.localhost`,
    publicPath: 'https://subdomain.localhost/',
    port: 9000,
    https: false,
    contentBase: path.join(__dirname),
    watchContentBase: true,
    historyApiFallback: true,
    compress: true,
    hot: true
  };
  </code></pre>
  
  <p><em>What configuration is required to ensure update manifest will load from the correct path?</em></p>
  
  <ul>
  <li><p>No other parts of our dev/prod environments are failing… which leads
  me to believe the configuration error exists in a niche. </p></li>
  <li><p><a href="https://subdomain.localhost/webpack-dev-server" rel="nofollow noreferrer">https://subdomain.localhost/webpack-dev-server</a> links to valid assets
  at the correct URL's</p></li>
  </ul>