Description of problem:
$ sudo -v
sudo: PAM authentication error: Module is unknown

Version-Release number of selected component (if applicable):
sudo-1.8.15-1.fc23.x86_64

How reproducible:
I can't see to fix it and there aren't any more updates, so I'm not sure what's going on.

Steps to Reproduce:
1. On 13 March 2016, run dnf --enablerepo=updates-testing upgrade
2. Reboot

Actual results:
Cannot run SUDO after update (even before reboot)

Expected results:
sudo shouldn't be broken

Additional info:
The reference to PAM makes me think I should mention than I have pam_yubico installed and configured for sudo.  However, it's been that way for 5 years or so, and I've never seen this error before.