Merge branch '6.x' into 7.x

Author: taylorotwell

src/Illuminate/Cache/FileStore.php

@@ -179,7 +179,9 @@ public function flush()
         }
 
         foreach ($this->files->directories($this->directory) as $directory) {
-            if (! $this->files->deleteDirectory($directory)) {
+            $deleted = $this->files->deleteDirectory($directory);
+
+            if (! $deleted || $this->files->exists($directory)) {
                 return false;
             }
         }