code: def _shutdown(self):
          
          global sconf_global, _ac_config_hs
  
          if not self.active:
              raise SCons.Errors.UserError("Finish may be called only once!")
          if self.logstream is not None and not dryrun:
              self.logstream.write("\n")
              self.logstream.close()
              self.logstream = None
          # remove the SConfSourceBuilder from the environment
          blds = self.env['BUILDERS']
          del blds['SConfSourceBuilder']
          self.env.Replace( BUILDERS=blds )
          self.active = 0
          sconf_global = None
          if not self.config_h is None:
              _ac_config_hs[self.config_h] = self.config_h_text
          self.env.fs = self.lastEnvFs
docs: Private method. Reset to non-piped spawn