当我运行apt-get update它会报告一个针对40976EAF437D05B5的BADSIG。 这是指一个包，还是指的是在我的钥匙圈gpg密钥？
如果我将/var/lib/apt/lists到/var/lib/apt/lists.old并重新运行apt-get ，问题就不存在了。 我怎样才能找出问题所在？
# apt-get update ... Hit http://ppa.launchpad.net trusty/main Translation-en Fetched 933 B in 1s (765 B/s) W: GPG error: http://apt.fammed.wisc.edu trusty Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <[email protected]> Current status: 0 broken [+0], 0 updates [+0], 605 new [+0].