class_docstr: Higher order selection rule using git ignored files.
  
  This is a 'select everything except ignored' rule and can be used
  in place of a select '*' select rule - with the exception that git
  ignored files are not selected.
code: def __str__(self):
      return "gitignore + guildignore patterns"
  
imports: import collections
  import logging
  import re
  import os
  import subprocess
  from guild import config
  from guild import file_util
  from guild import util
  from guild.file_util import FileSelectRule
label_desc: Use image node_id 2 for calling the _GitignoreSelectRule obj's underlying member method code with example usage: obj.__str__() and returns: str