# File lib/grit/git.rb, line 189
    def check_applies(head_sha, applies_sha)
      git_index = create_tempfile('index', true)
      options   = {:env => {'GIT_INDEX_FILE' => git_index}, :raise => true}
      status    = 0
      begin
        native(:read_tree, options.dup, head_sha)
        stdin = native(:diff, options.dup, "#{applies_sha}^", applies_sha)
        native(:apply, options.merge(:check => true, :cached => true, :input => stdin))
      rescue CommandFailed => fail
        status += fail.exitstatus
      end
      status
    end