Fix hot reloading for WebpackDevServer after eject (#1721)

packages/react-scripts/config/webpack.config.dev.js

@@ -123,7 +123,13 @@ module.exports = {
       {
         exclude: [
           /\.html$/,
-          /\.(js|jsx)$/,
+          // We have to write /\.(js|jsx)(\?.*)?$/ rather than just /\.(js|jsx)$/
+          // because you might change the hot reloading server from the custom one
+          // to Webpack's built-in webpack-dev-server/client?/, which would not
+          // get properly excluded by /\.(js|jsx)$/ because of the query string.
+          // Webpack 2 fixes this, but for now we include this hack.
+          // https://github.com/facebookincubator/create-react-app/issues/1713
+          /\.(js|jsx)(\?.*)?$/,
           /\.css$/,
           /\.json$/,
           /\.svg$/