code: def _init_class_from_url(self):
          
          from bugzilla import RHBugzilla
          if isinstance(self, RHBugzilla):
              return
  
          c = None
          if "bugzilla.redhat.com" in self.url:
              log.info("Using RHBugzilla for URL containing bugzilla.redhat.com")
              c = RHBugzilla
          else:
              try:
                  extensions = self._proxy.Bugzilla.extensions()
                  if "RedHat" in extensions.get('extensions', {}):
                      log.info("Found RedHat bugzilla extension, "
                          "using RHBugzilla")
                      c = RHBugzilla
              except Fault:
                  log.debug("Failed to fetch bugzilla extensions", exc_info=True)
  
          if not c:
              return
  
          self.__class__ = c
docs: Detect if we should use RHBugzilla class, and if so, set it