While looking through sytests, there seems to be a concept of storing/updating the next_batch of previous syncs with user objects (CSAPI objects in complement)

This could be quite helpful when "checkpointing" sync to a particular moment in the test fairly easily.

However, i suspect that adding this would be a massive breaking internal change, as every test in complement has basically acted with since: null up until this point.

Either that, or add an additional bool to every Sync* function which signifies if it should try to continue from the last-stored next_batch variable.