refs #6429 clean submodules before fetching any data [skip-ci]

plugins/TestRunner/Runner/Remote.php

@@ -28,10 +28,10 @@ class Remote
         $this->ssh->exec('git reset --hard');
         $this->ssh->exec('git submodule foreach --recursive git reset --hard');
         $this->ssh->exec('git clean -d -f');
+        $this->ssh->exec('git submodule foreach git clean -f');
         $this->ssh->exec('git fetch --all');
         $this->ssh->exec('git checkout ' . trim($gitHash));
         $this->ssh->exec('git submodule update --recursive --force');
-        $this->ssh->exec('git submodule foreach git clean -f');
         $this->ssh->exec('composer.phar install');
     }