[bug] fix webpack dev server memfs serving

packages/electrode-archetype-react-app-dev/lib/dev-admin/middleware.js

@@ -183,7 +183,9 @@ class Middleware {
     this.publicPath = webpackDevOptions.publicPath || "/";
     this.listAssetPath = urlJoin(this.publicPath, "/");
 
-    this.cwdMemIndex = serveIndex(process.cwd(), {
+    // webpack dev middleware's memfs root is where the actual output from webpack
+    this.memFsCwd = "/";
+    this.cwdMemIndex = serveIndex(this.memFsCwd, {
       icons: true,
       hidden: true,
       fs: this.devMiddleware.fileSystem
@@ -322,10 +324,10 @@ doReload(1); </script></body></html>`)
       );
     }
 
-    const serveStatic = (baseUrl, fileSystem, indexServer) => {
+    const serveStatic = (baseUrl, fileSystem, indexServer, cwd) => {
       req.originalUrl = req.url; // this is what express saves to, else serve-index nukes
       req.url = req.url.substr(baseUrl.length) || "/";
-      const fullPath = Path.join(process.cwd(), req.url);
+      const fullPath = Path.join(cwd || process.cwd(), req.url);
 
       return new Promise((resolve, reject) => {
         fileSystem.stat(fullPath, (err, stats) => {
@@ -407,7 +409,8 @@ ${listDirectoryHtml(this.listAssetPath, outputPath)}
       return serveStatic(
         this.cwdContextBaseUrl,
         this.devMiddleware.fileSystem,
-        this.cwdMemIndex
+        this.cwdMemIndex,
+        this.memFsCwd
       ).catch(err => sendStaticServeError("reading webpack mem fs", err));
     } else if (req.url.startsWith(this.reporterUrl) || this.returnReporter) {
       return serveReporter(this.webpackDev.lastReporterOptions);