@kode54 I reproduced the bug of repos appearing empty in git-ssb-web, and published a fix: %KLhr629.... Does that work for you?

For the first error you mentioned (EPIPE), that may be a trivial bug (output if there is nothing to push) or something else. If it happens again, retry with -vvv git argument so we can see more debug info.

For the second error (mentioning non-fast-forward), that is because git does not let you push a commit to a branch that is not a descendent of the current commit at that branch unless you force-push. To force-push, use -f (e.g. git push -f ssb master) or a plus (e.g. git push ssb +3796b03e7cca3a486a8bbe5974532f14242cea4b:master).

The 5MB limit of packfile blobs does not apply in the case you described. Packfiles in the .git directory are not necessarily what gets published by git-ssb. Also, you don't have to push existing repo content to the fork, because the fork already "inherits" the content and refs of the upstream repo.