Changes rolled back immediately after commit

Hello. Thank you for this library.

I can not find solution via google for next problem:

After Rugged::Commit.create changes rolled back immediately.

I have create test method and test repository

Try write changes to existing file 'index.md'

def create_commit
  repo = Rugged::Repository.new('TB 2')
  puts 'Init repository'
  puts '. . . . . . . . . . . .'

  changes = "- - - - - - \n test blob"

  oid = repo.write(changes, :blob)
  index = repo.index
  index.read_tree(repo.head.target.tree)
  index.add(:path => 'index.md', :oid => oid, :mode => 0100644)

  author = {:email => 'current_user.email', :time=>Time.now, :name => 'current_user.email'}
  options = {}
  options[:tree] = index.write_tree(repo)

  options[:author] = author
  options[:committer] = author
  options[:message] ||= "Edit page test"
  options[:parents] = repo.empty? ? [] : [ repo.head.target ].compact
  options[:update_ref] = 'HEAD'

  commit_result = Rugged::Commit.create(repo, options)
  puts commit_result.inspect

  puts '. . . . . . . . . . . . <'
end

Repository before changes:

Execute method:

$ irb
> load './rugged_test.rb'
=> true

> create_commit
. . . . . . . . . . . .
"0e7891687e9aa0a3868c29046dbd033767ae2aca"
. . . . . . . . . . . . <
=> nil

Repository after changes:

Rugged version:

    ...

    Installing rugged 0.21.4

    ...

I am not good know git itself, but use instructions from Rugged Readme page. Looks like i have missing some additional step in setup or commit, but i can not figure out which of.

Start by running the supplied create_commit reproduction against the test repository and inspect Rugged::Commit.create, repo.index, and the HEAD update path. Compare the commit's tree and HEAD before and after reopening the repository; done means the written index.md content remains present after the method returns.