The GPG key I would expect to be here, http://yum.theforeman.org/releases/1.17/, is missing. This breaks the yumrepo resources added by puppet-foreman module when attempting to upgrade to 1.17 repos.
I have worked around the problem on our local mirror of Foreman repos by downloading https://raw.githubusercontent.com/theforeman/foreman-packaging/rpm/1.17/foreman/foreman.gpg to the place where RPM-GPG-KEY-foreman should exist.