whimboo/mozmill-ci — pull request #11 by whimboo (2012-03-26 20:33:18+00:00)
Title: Ensure that the downloaded version of Jenkins is always up-to-date. Fixes issue #9

So you were right. Adding '-z FILENAME' is the solution here and works fine. I only was confused by the initial warning you will get, but that's expected as given by the curl documentation.