yummain.user_main(sys.argv[1:], exit_code=True)

yum update 时报错，报错信息如下：
File "/usr/bin/yum", line 29, in ?
    yummain.user_main(sys.argv[1:], exit_code=True)
  File "/usr/share/yum-cli/yummain.py", line 229, in user_main
    errcode = main(args)
  File "/usr/share/yum-cli/yummain.py", line 104, in main
    result, resultmsgs = base.doCommands()
  File "/usr/share/yum-cli/cli.py", line 339, in doCommands
    self._getTs(needTsRemove)
  File "/usr/lib/python2.4/site-packages/yum/depsolve.py", line 101, in _getTs
    self._getTsInfo(remove_only)

网上说，这个是yum的一个bug，解决办法是停掉fastestmirror 插件：
yum --disableplugin=fastestmirror update