paramiko AttributeError: 'NoneType' object has no attribute 'time'

报错信息：

Exception ignored in: <function BufferedFile.__del__ at 0xffff8810f280>
Traceback (most recent call last):
  File "/home/test/.local/lib/python3.9/site-packages/paramiko/file.py", line 66, in __del__
  File "/home/test/.local/lib/python3.9/site-packages/paramiko/channel.py", line 1392, in close
  File "/home/test/.local/lib/python3.9/site-packages/paramiko/channel.py", line 991, in shutdown_write
  File "/home/test/.local/lib/python3.9/site-packages/paramiko/channel.py", line 967, in shutdown
  File "/home/test/.local/lib/python3.9/site-packages/paramiko/transport.py", line 1900, in _send_user_message
AttributeError: 'NoneType' object has no attribute 'time'

添加：stdin.close()

#!/usr/bin/env python3
# -*- coding:utf-8 -*-

import paramiko
 
ssh= paramiko.SSHClient()#创建SSH对象
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())#允许连接不在know_hosts文件中的主机
ssh.connect(hostname='192.168.2.1', port=22, username='root', password='12345678')#连接服务器
 
stdin, stdout, stderr= ssh.exec_command('pwd')#执行命令并获取命令结果
stdin.close()
#stdin为输入的命令
#stdout为命令返回的结果
#stderr为命令错误时返回的结果
res, err= stdout.read(), stderr.read()
result= res if res else err
print(result)
ssh.close()#关闭连接