Patch hostname in configuration file even if name is unsync

Ref https://github.com/GNS3/gns3-gui/issues/1889

gns3server/compute/dynamips/nodes/router.py

@@ -24,6 +24,7 @@ import asyncio
 import time
 import sys
 import os
+import re
 import glob
 import shlex
 import base64
@@ -1493,7 +1494,7 @@ class Router(BaseNode):
                 try:
                     with open(startup_config_path, "r+", encoding="utf-8", errors="replace") as f:
                         old_config = f.read()
-                        new_config = old_config.replace(self.name, new_name)
+                        new_config = re.sub(r"^hostname .+$", "hostname " + new_name, old_config, flags=re.MULTILINE)
                         f.seek(0)
                         self._startup_config_content = new_config
                         f.write(new_config)