DHCPd keeps reassigning IP addresses / breaks IPMI power control

This bug is probably related to https://bugs.launchpad.net/maas/+bug/2025468 which is supposedly fixed. That said, we're on Maas 3.4 RC2 current as of 11/9/2023 and the problem persists.

** Effect

After some time (typically 24h) after commissioning a machine, it reports the following error:

'''
Failed to query node's BMC - Connection timed out while performing power action. Check BMC configuration and connectivity and try again.
'''

** Cause

The DHCPd reassigns a new IP number to an existing MAC address, yet Maas doesn't keep track of this. This is likely due to a broken maas-helper script. An example of it is below (this is from dhcpd.leases):

'''
lease 192.168.29.237 {
  starts 2 2023/11/07 18:44:44;
  ends 2 2023/11/07 18:46:44;
  tstp 2 2023/11/07 18:44:20;
  tsfp 2 2023/11/07 18:49:20;
  atsfp 2 2023/11/07 18:49:20;
  cltt 2 2023/11/07 18:44:44;
  binding state free;
  hardware ethernet ac:1f:6b:b6:a4:a4;
  set vendor-class-identifier = "udhcp 1.23.1";
  client-hostname "disk-27.ipmi.canada.boson.ai";
  on expiry {
    set clhw =
       binary-to-ascii (16, 8, ":",
                        substring (hardware, 1, 6)) ;
    set clip =
       binary-to-ascii (10, 8, ".", leased-address) ;
    execute ("/usr/sbin/maas-dhcp-helper", "notify", "--action", "expiry",
        "--mac", clhw, "--ip-family", "ipv4", "--ip", clip, "--socket", "/var/lib/maas/dhcpd.sock");
  }
  on release {
    set clhw =
       binary-to-ascii (16, 8, ":",
                        substring (hardware, 1, 6)) ;
'''

After the initial (correct assignment to 192.168.29.237) later on the machine is assigned a new IP address as follows:

'''
}
lease 192.168.30.169 {
  starts 3 2023/11/08 19:45:03;
  ends 3 2023/11/08 19:55:03;
  tstp 5 2023/10/06 02:33:42;
  tsfp 3 2023/11/08 20:00:03;
  atsfp 3 2023/11/08 20:00:03;
  binding state active;
  next binding state expired;
  hardware ethernet ac:1f:6b:b6:a4:a4;
}
'''

Note that we're in a subnet 255.255.252.0 with 1024 IP numbers, hence 192.168.29.237 and 192.168.30.169 are in the same subnet for what Maas is concerned. I posted on https://discourse.maas.io/t/dhcpd-forgets-about-ipmi-ip-addresses-maas-3-4-ipmi-power-error/7582 but did not get any replies, hence cross-posting here.