Make it easy to run split build/publish infrastructure
F-Droid's own repo uses a split build/publish infrastructure which provides a considerable amount of extra security. The build section is almost offline, being allowed outbound access only to retrieve source code for building from. The publish section is isolated from even that, and can be totally offline.
Although the fdroidserver tools fully support this setup, there's no documentation on how to use them effectively to do so, and no standard set of glue scripts to make it all happen seamlessly.