ntpq mrulist is broken

There are several symptoms.

ntpq> mru
Ctrl-C will stop MRU retrieval and display partial results.
Command `mrulist' is unknown
ntpq> 
[There are active slots on this system.

---

ntpq> mrulist
Ctrl-C will stop MRU retrieval and display partial results.
Traceback (most recent call last):
  File "/usr/local/bin/ntpq", line 1722, in <module>
    interpreter.cmdloop()
  File "/usr/lib64/python3.7/cmd.py", line 138, in cmdloop
    stop = self.onecmd(line)
  File "/usr/lib64/python3.7/cmd.py", line 217, in onecmd
    return func(arg)
  File "/usr/local/bin/ntpq", line 1256, in do_mrulist
    rawhook=mruhook, direct=direct)
  File "/usr/local/lib64/python3.7/site-packages/ntp/packet.py", line 1497, in mrulist
    stitch_mru(span, sorter, sortkey)
  File "/usr/local/lib64/python3.7/site-packages/ntp/packet.py", line 1595, in stitch_mru
    deletia += sorted(addrdict[addr], key=lambda x: x[1])[:-1]
TypeError: '<' not supported between instances of 'NoneType' and 'NoneType'
[murray@hgm ~]$