Issue #23865: close() methods in multiple modules now are idempotent and more

robust at shutdown. If needs to release multiple resources, they are released
even if errors are occured.

Lib/telnetlib.py

@@ -261,12 +261,13 @@ class Telnet:
 
     def close(self):
         """Close the connection."""
-        if self.sock:
-            self.sock.close()
-        self.sock = 0
-        self.eof = 1
+        sock = self.sock
+        self.sock = None
+        self.eof = True
         self.iacseq = b''
         self.sb = 0
+        if sock:
+            sock.close()
 
     def get_socket(self):
         """Return the socket object used internally."""