Some branches (including one used in the Spright Fright production) require a certain add-ons branch to be used. So far the way to do this was by setting a submodule branch in Blender's make update. E.g. like here rB build_files/utils/make_update.py:177-183 (on asset-browser-poselib):
submodules = [ ("release/scripts/addons", "asset-browser-poselib"), ("release/scripts/addons_contrib", branch), ("release/datafiles/locale", branch), ("source/tools", branch), ]
The new buildbot doesn't checkout the branch as specified anymore, meaning the builds might not be usable for testing.
In the Blender Studio, animators use this to work with the asset-browser-poselib branch, which is developed in partnership with Spright Fright production.