Fix path config:export on root Drupal (#4153)

Author: gilbertomangones

src/Command/Config/ExportCommand.php

@@ -98,14 +98,15 @@ protected function execute(InputInterface $input, OutputInterface $output)
         $tar = $input->getOption('tar');
         $removeUuid = $input->getOption('remove-uuid');
         $removeHash = $input->getOption('remove-config-hash');
+        $drupal_root = $this->drupalFinder->getComposerRoot();
 
         if (!$directory) {
             $directory = config_get_config_directory(CONFIG_SYNC_DIRECTORY);
         }
 
         $fileSystem = new Filesystem();
         try {
-            $fileSystem->mkdir($directory);
+            $fileSystem->mkdir($drupal_root."/".$directory);
         } catch (IOExceptionInterface $e) {
             $this->getIo()->error(
                 sprintf(