等待百胜...
其中一个已配置的存储库失败（Fedora 21 - x86_64）， 并且yum没有足够的缓存数据来继续。此时唯一 百胜可以做的安全事情就是失败。有几种方法可以解决＆＃34;修复＆＃34;这样：
1. Contact the upstream for the repository and get them to fix the problem.
2. Reconfigure the baseurl/etc. for the repository, to point to a working
upstream. This is most often useful if you are using a newer
distribution release than is supported by the repository (and the
packages for the previous distribution release still work).
3. Disable the repository, so yum won't use it by default. Yum will then
just ignore the repository until you permanently enable it again or use
--enablerepo for temporary usage:
yum-config-manager --disable fedora-21
4. Configure the failing repository to be skipped, if it is unavailable.
Note that yum will try to contact the repo. when it runs most commands,
so will have to try and fail each time (and thus. yum will be be much
slower). If it is a very temporary problem though, this is often a nice
compromise:
yum-config-manager --save --setopt=fedora-21.skip_if_unavailable=true
无法检索存储库的metalink：fedora-21 / x86_64。请验证其路径，然后重试
错误：子进程退出代码1