[DiapDealer]

Yes. From the very beginning, Sigil's checkpointing system created github repositories via python's dulwich module. The repositories do not contain binary blobs of the epub. That would be pointless, as there could be no meaningful diffs generated. The repositories are comprised of the individual contents of the expanded EPUB archive--easily diffed from checkpoint to checkpoint (and accessible via external tools--including git--if desired).

It seems to me that people (and I'm not singling out the OP here by any means) seem to really go out of their way to avoid using one of the most useful features that I think has been added to Sigil in a long time. It just seems that many people tend to suggest improvements to Sigil that can already be done via the checkpoint system.