The protocol design allows the server to respond with some other object;
if a server for some reason a server did that, it would not be right for
git-annex to download its content. I don't think it would be a security
hole, since git-annex is downloading a specific key and will verify the
key's content. Seems like a good idea to belt-and-suspenders test for
such a misuse of the protocol.
This is a special remote and a git remote at the same time; git can pull
and push to it and git-annex can use it as a special remote.
Remote.Git has to check if it's configured as a git-lfs special remote
and sets it up as one if so.
Object methods not implemented yet.
