
The last rebuild only promoted our Gerrit 3.8 image. This appears to have happened because we only modified the jobs and not the Dockerfile itself. Fix this by modifying the Dockerfile which should rebuild and promote both 3.8 and 3.9 images ensuring that our upgrade testing tests what we want to upgrade to. Change-Id: I8d06ea9971a6ee0c0e06e6fe2b73391526be6220