Using the default release for the Debian test-element leaves
us at the mercy of packaging problems in Debian unstable. Since
we only care if the image itself builds, use the safe choice of
Debian stable.
Change-Id: I4dd58171489aa07d60db7e4e353ccde6aa534da7
Weve had some regressions recently with the changes in the debian
element. Lets tests that we can build debian images.
Change-Id: I048e7a32ecb4088ec1b1e3b1efdf146187b093db