Python-Dev无法在Ubuntu Trusty上安装

Question

我试图安装let-encrypt导致我需要安装python2.7-dev。然而，这失败了以下错误。任何帮助非常感谢：

The following packages have unmet dependencies:
 python2.7-dev : Depends: python2.7 (= 2.7.6-8) but 2.7.6-8ubuntu0.2 is to be installed
                 Depends: libpython2.7-dev (= 2.7.6-8) but 2.7.6-8ubuntu0.2 is to be installed
                 Depends: libpython2.7 (= 2.7.6-8) but 2.7.6-8ubuntu0.2 is to be installed

政策的输出：

$ apt-cache policy python2.7
python2.7:
  Installed: 2.7.6-8ubuntu0.2
  Candidate: 2.7.6-8ubuntu0.2
  Version table:
 *** 2.7.6-8ubuntu0.2 0
        100 /var/lib/dpkg/status
     2.7.6-8 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/main amd64 


apt-cache policy python2.7-dev
python2.7-dev:
  Installed: (none)
  Candidate: 2.7.6-8
  Version table:
     2.7.6-8 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages