我刚刚do-release-upgrade从 Ubuntu 16.04 升级到 17.04。但是，现在当我通过 SSH 登录时，我收到以下消息
Welcome to Ubuntu 17.04 (GNU/Linux 4.10.0-20-generic x86_64)
* Documentation: https://help.ubuntu.com
* Management: https://landscape.canonical.com
* Support: https://ubuntu.com/advantage
Ubuntu 12.04 LTS end-of-life was April 28, 2017 -- Upgrade your Precise systems!
$ sudo do-release-upgrade -m server
0 packages can be updated.
0 updates are security updates.
我的问题是，如何删除
Ubuntu 12.04 LTS end-of-life was April 28, 2017 -- Upgrade your Precise systems!
$ sudo do-release-upgrade -m server
它在发布升级之前不存在
我查了一下，我在 Zesty 上
lsb_release -a
No LSB …