Allow the dev server to watch for changes in src/node_modules

Author: xjlim

packages/react-scripts/config/webpackDevServer.config.js

@@ -72,8 +72,10 @@ module.exports = function(proxy, allowedHost) {
     quiet: true,
     // Reportedly, this avoids CPU overload on some systems.
     // https://github.com/facebookincubator/create-react-app/issues/293
+    // src/node_modules is not ignored to support absolute imports
+    // https://github.com/facebookincubator/create-react-app/issues/1065
     watchOptions: {
-      ignored: /node_modules/,
+      ignored: new RegExp(`^(?!${paths.appSrc})*[\\\/]node_modules[\\\/]`, 'g'),
     },
     // Enable HTTPS if the HTTPS environment variable is set to 'true'
     https: protocol === 'https',