Currently, if a repository is missing LFS data for older versions of files, it's impossible to push it to a new endpoint. I think the git lfs push and pre-push commands should spew errors if it can't find an object locally, without halting the push operation early. The commands should still return with a non-zero exit code, but at least the other objects have a chance to be uploaded. This allows repositories with missing objects to be easily fixed without resorting to git filter-branch.

This is also a small baby step towards Object Expiration (as described in #1101 (comment)), which would let repository owners mark certain OIDs as known missing objects. By marking an object as expired, the push and pre-push commands will just skip the upload attempt, so the commands can return successfully.

Finally, double check that upload retries reset the progress meter properly.