1) Why do we log here as warning, if it is obviously an error? (look at the whole file) That's the question to other places where we run task, I understand that you just copy-pasted. And, why don't we log the full traceback?
2) We really need to start better documenting. Please make an effort, and make beautiful docstring for task/task.py DownloadReleaseTask execute method, show the params we pass to Naily and good explanation for each parameter.