fix 404 error on homepage

fix_404_error_on_homepage.patch

Index: vendor/magento/module-page-cache/Model/App/FrontController/BuiltinPlugin.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- src/vendor/magento/module-page-cache/Model/App/FrontController/BuiltinPlugin.php	(date 1568877775000)
+++ src/vendor/magento/module-page-cache/Model/App/FrontController/BuiltinPlugin.php	(date 1568877794582)
@@ -69,7 +69,7 @@
             return $proceed($request);
         }
         $result = $this->kernel->load();
-        if ($result === false) {
+        if ($result === false || ($result instanceof ResponseHttp && $result->getStatusCode() == 404)) {
             $result = $proceed($request);
             if ($result instanceof ResponseHttp) {
                 $this->addDebugHeaders($result);