saltstack redis returner is complaining when trying to delete keys?

master.log

2016-12-07 21:22:05,549 [salt.utils.process][ERROR   ] An un-handled exception from the multiprocessing process 'Maintenance-9' was caught:
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/salt/utils/process.py", line 623, in _run
    return self._original_run()
  File "/usr/lib/python2.7/dist-packages/salt/master.py", line 237, in run
    salt.daemons.masterapi.clean_old_jobs(self.opts)
  File "/usr/lib/python2.7/dist-packages/salt/daemons/masterapi.py", line 187, in clean_old_jobs
    mminion.returners[fstr]()
  File "/usr/lib/python2.7/dist-packages/salt/returners/redis_return.py", line 220, in clean_old_jobs
    serv.delete(*to_remove)
  File "/usr/lib/python2.7/dist-packages/redis/client.py", line 421, in delete
    return self.execute_command('DEL', *names)
  File "/usr/lib/python2.7/dist-packages/redis/client.py", line 361, in execute_command
    return self.parse_response(connection, command_name, **options)
  File "/usr/lib/python2.7/dist-packages/redis/client.py", line 371, in parse_response
    response = connection.read_response()
  File "/usr/lib/python2.7/dist-packages/redis/connection.py", line 311, in read_response
    raise response
ResponseError: wrong number of arguments for 'del' command