When deploying a new builder in Fedora infrastructure I'm now seeing the following startup issue with koji 0.12.0

koji-1.12.0-1.fc25.noarch
koji-builder-1.12.0-1.fc25.noarch
koji-containerbuild-builder-0.6.6-3.fc25.noarch
koji-containerbuild-0.6.6-3.fc25.noarch

Started Koji build server.
kojid[1002]: Traceback (most recent call last):
kojid[1002]: File "/usr/sbin/kojid", line 5627, in <module>
kojid[1002]: if os.path.isfile(options.cert):
kojid[1002]: File "/usr/lib/python2.7/genericpath.py", line 37, in isfile
kojid[1002]: st = os.stat(path)
kojid[1002]: TypeError: coercing to Unicode: need string or buffer, NoneType found
systemd[1]: kojid.service: Main process exited, code=exited, status=1/FAILURE
systemd[1]: kojid.service: Unit entered failed state.
systemd[1]: kojid.service: Failed with result 'exit-code'.