升级后yum无法使用

执行了一次yum -y update升级完后就这样了，提示信息：
Traceback (most recent call last):
  File "/usr/bin/yum", line 29, in <module>
    yummain.main(sys.argv[1:])
  File "/usr/share/yum-cli/yummain.py", line 85, in main
    base.getOptionsConfig(args)
  File "/usr/share/yum-cli/cli.py", line 154, in getOptionsConfig
    disabled_plugins=opts.disableplugins)
  File "/usr/lib/python2.5/site-packages/yum/__init__.py", line 164, in _getConfig
    self.getReposFromConfig()
  File "/usr/lib/python2.5/site-packages/yum/__init__.py", line 229, in getReposFromConfig
    parser.readfp(confpp_obj)
  File "/usr/lib/python2.5/site-packages/iniparse/compat.py", line 106, in readfp
    self.data.readfp(fp)
  File "/usr/lib/python2.5/site-packages/iniparse/ini.py", line 563, in readfp
    if line and line[-1]=='\n':
UnboundLocalError: local variable 'line' referenced before assignment
另外rpm的gui程序也不能用了