prevent layout cache corruption

Author: scottsb

lib/internal/Magento/Framework/View/Model/Layout/Merge.php

@@ -427,6 +427,9 @@ public function load($handles = [])
         if ($result) {
             $this->addUpdate($result);
             $this->pageLayout = $this->_loadCache($cacheIdPageLayout);
+            foreach ($this->getHandles() as $handle) {
+                $this->allHandles[$handle] = $this->handleProcessed;
+            }
             return $this;
         }