Protect against corner case where rename happens into a subdir of the session

engine/nsmservercontrol.py

@@ -37,6 +37,7 @@ import subprocess
 import atexit
 import pathlib
 import json
+from uuid import uuid4
 from datetime import datetime
 from sys import exit as sysexit
 
@@ -1362,8 +1363,11 @@ class NsmServerControl(object):
             logger.warning(f"Can't rename {nsmSessionName} to {newName}. {newName} already exists.")
             return False
         else:
-            logger.info(f"Renaming {nsmSessionName} to {newName}.")
-            oldPath.rename(newPath)
+            logger.info(f"Renaming {nsmSessionName} to {newName}.")            
+            tmp = pathlib.Path(oldPath.name+str(uuid4())) #Can't move itself into a subdir in itself. move to temp first. We don't use tempdir because that could be on another partition. we already know we can write here.            
+            oldPath.rename(tmp)
+            pathlib.Path(newPath).mkdir(parents=True, exist_ok=True)
+            tmp.rename(newPath)            
             assert newPath.exists()
 
     def copySession(self, nsmSessionName:str, newName:str):