PDK nightly builds just started picking up Facter 4 and our acceptance tests are failing in the scenario where the PDK package has been installed on a system as root but then an unprivileged user is running commands. It appears Facter is trying to create a log file inside the gem installation path by default.
The log file was removed because it is not required anymore. Other projects that use Facter can pass in their logger via Facter.on_message(&block) API.