yum 错误：无法导入名称 ts

Question

在 yum 更新期间，我们的一台服务器突然断电，现在尝试运行 yum 会产生以下问题：

# yum update
error: Failed to initialize NSS library

There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:

    cannot import name ts

Please install a package which provides this module, or
verify that the module is installed correctly.

It's possible that the above module doesn't match the
current version of Python, which is:
2.7.5 (default, Aug 4 2017, 08:39:18)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-16)]

If you cannot solve this problem yourself, please go to
the yum faq at:
  http://yum.baseurl.org/wiki/Faq

我可以看到“ts”位于 site-packages/rpm/transaction.py 中，并且它位于 python-2.7 下（与当前 python 版本匹配）。有没有人见过这个问题并找到了可行的解决方案？

---更新 1---

通过 rsyncing 另一个工作系统的站点包目录解决了这个直接错误，但现在出现了不同的错误：

  /usr/lib64/python2.7/site-packages/rpm/_rpm.so: undefined symbol: rpmtsAddReinstallElement

事实证明，这一点更难确定。

谢谢！