@xloem ok, sounds like something messed up. I assume this is repo %Tb/JpME.... Cloning it normally fails also, which may be another issue.

I found the upstream repo but have not been able to reproduce the unresolved deltas error. What is the next commit you are trying to push? What is your git version?

Some updates to the chunking instructions:
Instead of picking commits from the log to push, you could push tags. That may be a little more organized, and gets the tags pushed.
If you installed git-ssb from ssb-npm, it will detect and prevent pushing a packfile blob > 5MB (overridable with git push option -o force). So using DRY_RUN=1 is not necessary in that case.