Only honor relative NODE_PATH (facebook#1194)

Author: gaearon

packages/react-scripts/config/paths.js

@@ -33,9 +33,14 @@ function resolveApp(relativePath) {
 // It will then be used by Webpack configs.
 // Jest doesn’t need this because it already handles `NODE_PATH` out of the box.
 
+// Note that unlike in Node, only *relative* paths from `NODE_PATH` are honored.
+// Otherwise, we risk importing Node.js core modules into an app instead of Webpack shims.
+// https://github.com/facebookincubator/create-react-app/issues/1023#issuecomment-265344421
+
 var nodePaths = (process.env.NODE_PATH || '')
   .split(process.platform === 'win32' ? ';' : ':')
   .filter(Boolean)
+  .filter(folder => !path.isAbsolute(folder))
   .map(resolveApp);
 
 // config after eject: we're in ./config/