https://github.com/facebookincubator/create-react-app/pull/1588

patch-cra-set-public-path.js

const fs = require("fs");

const pathClient = "./node_modules/react-dev-utils/webpackHotDevClient.js";

fs.writeFileSync(
  pathClient,
  fs
    .readFileSync(pathClient)
    .toString()
    .replace(
      `var connection = new SockJS(
  url.format({
    protocol: window.location.protocol,
    hostname: window.location.hostname,
    port: window.location.port,
    // Hardcoded in WebpackDevServer
    pathname: '/sockjs-node',
  })
);`,
      `
var scriptUrl = document.currentScript
? url.parse(document.currentScript.src)
: window.location;
var connection = new SockJS(
  url.format({
    protocol: scriptUrl.protocol,
    hostname: scriptUrl.hostname,
    port: scriptUrl.port,
    // Hardcoded in WebpackDevServer
    pathname: '/sockjs-node',
  })
);`
    )
);

const pathConfig = "./node_modules/react-scripts/config/webpackDevServer.config.js";
fs.writeFileSync(
  pathConfig,
  fs
    .readFileSync(pathConfig)
    .toString()
    .replace(
      `const publicPath = '/';`,
      `const publicPath = process.env.PUBLIC_PATH || '/';`
    )
);