in spec/repository_spec.rb [1169:1183]
def new_commit_move_file(repo)
blob_oid = repo.head.target.tree.detect { |i| i[:name] == "CHANGELOG" }[:oid]
file_content = repo.lookup(blob_oid).content
oid = repo.write(file_content, :blob)
index = repo.index
index.read_tree(repo.head.target.tree)
index.add(path: "encoding/CHANGELOG", oid: oid, mode: 0100644)
index.remove("CHANGELOG")
options = commit_options(repo, index, "Move CHANGELOG to encoding/")
sha = Rugged::Commit.create(repo, options)
repo.lookup(sha)
end