def prepare
      raise AlreadyPreparedError.new(@path) if prepared?
      in_work_tree :tmp do
        FileUtils.touch '.silo'
        @git.add '.silo'
        @git.commit_index 'Enabled Silo for this repository'
      end
    end
def prepare
      raise AlreadyPreparedError.new(@path) if prepared?
      in_work_tree :tmp do
        FileUtils.touch '.silo'
        @git.add '.silo'
        @git.commit_index 'Enabled Silo for this repository'
      end
    end
Prepares the Git repository backing this Silo repository for use with
 Silo

 @raise [AlreadyPreparedError] if the repository has been already prepared