after adding namer callable (like it is described in https://bugs.python.org/issue43344) to log handler configuration, it stopped removing old files

log_filename = os.path.join(log_dir, "application.log")
log_handler = logging.handlers.TimedRotatingFileHandler(log_filename, when='MIDNIGHT', interval=1, backupCount=7)

// after adding this line, old files are not deleted
log_handler.namer = lambda name: name.replace(".log", "") + ".log"