fix: Return empty list when there is no content in res_ks_list

src/mrack/transformers/beaker.py

@@ -152,9 +152,7 @@ def _construct_ks_append_script(self, ks_append, pubkeys=None):
         if pubkeys:
             res_ks_list += ["%post"] + self._allow_ssh_keys(pubkeys) + ["%end"]
 
-        return [
-            "\n".join(res_ks_list),
-        ]
+        return ["\n".join(res_ks_list)] if res_ks_list else []
 
     def _allow_ssh_keys(self, pubkeys):
         """Create ssh key content to be injected to xml."""