After updating to RHEL 7.x, rpm and yum command fails with "Failed to initialize NSS library"

Issue

• rpm and yum fail with "error: Failed to initialize NSS library"

  # rpm -qa
  error: Failed to initialize NSS library
  
  # rpm -Va
  error: Failed to initialize NSS library
  
  # 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, May  3 2017, 07:55:04) 
  [GCC 4.8.5 20150623 (Red Hat 4.8.5-14)]
  
  If you cannot solve this problem yourself, please go to 
  the yum faq at:
    http://yum.baseurl.org/wiki/Faq