code: def auto_detect(workdir):
      
      # Any additions here also need a change to `SCM_PROVIDERS`!
      if os.path.isdir(os.path.join(workdir, '.git')) and os.path.isfile(os.path.join(workdir, '.git', 'HEAD')):
          return 'git'
  
      return 'unknown'
docs: Return string signifying the SCM used in the given directory.
  
          Currently, 'git' is supported. Anything else returns 'unknown'.