in lib/rugged_adapter/git_layer_rugged.rb [465:478]
def commit(message, parents = nil, actor = nil, last_tree = nil, head = 'refs/heads/master')
commit_options = {}
head = "refs/heads/#{head}" if head && head !~ %r(^refs/heads/)
parents = get_parents(parents, head) || []
actor = Gollum::Git::Actor.default_actor if actor.nil?
commit_options[:tree] = @index.write_tree
commit_options[:author] = actor.to_h
commit_options[:committer] = actor.to_h
commit_options[:message] = message.to_s
commit_options[:parents] = parents
commit_options[:update_ref] = head
Rugged::Commit.create(@rugged_repo, commit_options)
end