I've searched around and can't find a real answer to this. If I create a docker git repo and set up autobuild to my dockerhub account, it will build with a single tag (i.e. latest, or 1.0 or foo) but I can't find any way to add a tag afterwards as you can via command line with a locally built docker image. Pulling down the image and then retagging doesn't work as the autobuild repos are read-only outside of the webui.
Being able to manually add a tag to an existing build would satisfy me for now, but being able to script in something to grab the correct tag version would be the best solution.