Canary builders are failing. E.g.
https://luci-milo.appspot.com/buildbot/chromeos/mccloud-release/1360 

The fail happens in;
https://cs.corp.google.com/chromeos_public/chromite/lib/paygen/paygen_payload_lib.py?sq&q=chromite/lib/paygen/paygen_payload_lib.py+package:%5Echromeos_public$&l=686
urilib.Copy's args must not be None, but self.payload.uri is None for some reasons, according to the log.