There was an error on exit if no sys.exitfunc was defined. Issue 1647.

Lib/idlelib/NEWS.txt

@@ -3,6 +3,8 @@ What's New in IDLE 2.6a1?
 
 *Release date: XX-XXX-2008*
 
+- There was an error on exit if no sys.exitfunc was defined. Issue 1647.
+
 - Could not open files in .idlerc directory if latter was hidden on Windows.
   Issue 1743, Issue 1862.
 

Lib/idlelib/run.py

@@ -206,7 +206,10 @@ def exit():
 
     """
     if no_exitfunc:
-        del sys.exitfunc
+        try:
+            del sys.exitfunc
+        except AttributeError:
+            pass
     sys.exit(0)
 
 class MyRPCServer(rpc.RPCServer):