Fix call to _write_file_sudo()

coriolis/osmorphing/debian.py

@@ -54,7 +54,7 @@ class BaseDebianMorphingTools(base.BaseLinuxOSMorphingTools):
         cfg.append_to_option(
             "GRUB_CMDLINE_LINUX",
             {"opt_type": "key_val", "opt_key": "biosdevname", "opt_val": 0})
-        self._write_file_sudo(grub_cfg, cfg.dump())
+        self._write_file_sudo("etc/default/grub", cfg.dump())
         self._exec_cmd_chroot("/usr/sbin/update-grub")
 
     def _compose_interfaces_config(self, nics_info):