当我尝试使用命令在我的 ubuntu 14.04 上安装 bison 时，安装sudo apt-get install bison了版本 3。
我想降级野牛以使用 2.7 版。
我该怎么做？
谢谢。
当我尝试从 Ubuntu Gnome 13.10 升级到 Ubuntu 14.04 时，升级应用程序失败并显示以下消息：
Could not calculate the upgrade.
An unresolvable problem occurred while calculating the upgrade.`
这是完整的日志：
$ cat /etc/issue
Ubuntu 13.10 \n \l
$ sudo apt-get update
$ sudo apt-get upgrade
$ sudo do-release-upgrade
Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Building data structures... Done
Calculating the changes
Calculating the changes
Could not calculate the upgrade
An unresolvable problem occurred while calculating the upgrade.
This can be …