kea logs error every time command channel command is received

1. setup is simple Kea4 + kea-ctrl-agent, configs at the bottom, important thing is that here I am sending commands on the same interface as dhcp traffic (in system tests we use separate networks)
2. send command via http to ctrl-agent, logs:

May 14 15:59:16 ubuntu20-64-1 kea-ctrl-agent: INFO  [kea-ctrl-agent.commands.140266868430400] COMMAND_RECEIVED Received command 'config-get'
May 14 15:59:16 ubuntu20-64-1 kea-ctrl-agent: INFO  [kea-ctrl-agent.ctrl-agent.140266868430400] CTRL_AGENT_COMMAND_FORWARDED command config-get successfully forwarded to the service dhcp4

kea-dhcp4 logs:

2020-05-14 15:59:16.351 ERROR [kea-dhcp4.packets/6770.140286406021056] DHCP4_BUFFER_RECEIVE_FAIL error on attempt to receive packet: received data over unknown socket
2020-05-14 15:59:16.351 INFO  [kea-dhcp4.commands/6770.140286406021056] COMMAND_RECEIVED Received command 'config-get'

4. commands actually works

[
  {
    "arguments": {
      "Control-agent": {
        "control-sockets": {
          "dhcp4": {
            "socket-name": "/tmp/control_socket",
            "socket-type": "unix"
          }
        },
        "hooks-libraries": [],
        "http-host": "192.168.59.2",
        "http-port": 8000,
        "loggers": [
          {
            "debuglevel": 0,
            "name": "kea-ctrl-agent",
            "output_options": [
              {
                "flush": true,
                "maxsize": 10240000,
                "maxver": 1,
                "output": "syslog",
                "pattern": ""
              }
            ],
            "severity": "INFO"
          }
        ]
      }
    },
    "result": 0
  }

[
  {
    "arguments": {
      "Dhcp4": {
        "authoritative": false,
        "boot-file-name": "",
        "calculate-tee-times": false,
        "config-control": {
          "config-databases": [
            {
              "name": "keatest",
              "password": "keatest",
              "type": "mysql",
              "user": "keatest"
            }
          ],
          "config-fetch-wait-time": 0
        },
        "control-socket": {
          "socket-name": "/tmp/control_socket",
          "socket-type": "unix"
        },
        "ddns-generated-prefix": "myhost",
        "ddns-override-client-update": false,
        "ddns-override-no-update": false,
        "ddns-qualifying-suffix": "",
        "ddns-replace-client-name": "never",
        "ddns-send-updates": true,
        "decline-probation-period": 86400,
        "dhcp-ddns": {
          "enable-updates": false,
          "max-queue-size": 1024,
          "ncr-format": "JSON",
          "ncr-protocol": "UDP",
          "sender-ip": "0.0.0.0",
          "sender-port": 0,
          "server-ip": "127.0.0.1",
          "server-port": 53001
        },
        "dhcp-queue-control": {
          "capacity": 500,
          "enable-queue": false,
          "queue-type": "kea-ring4"
        },
        "dhcp4o6-port": 0,
        "echo-client-id": true,
        "expired-leases-processing": {
          "flush-reclaimed-timer-wait-time": 25,
          "hold-reclaimed-time": 3600,
          "max-reclaim-leases": 100,
          "max-reclaim-time": 250,
          "reclaim-timer-wait-time": 10,
          "unwarned-reclaim-cycles": 5
        },
        "hooks-libraries": [
          {
            "library": "/home/wlodek/kea_bin/lib/kea/hooks/libdhcp_mysql_cb.so"
          },
          {
            "library": "/home/wlodek/kea_bin/lib/kea/hooks/libdhcp_cb_cmds.so"
          }
        ],
        "host-reservation-identifiers": [
          "hw-address",
          "duid",
          "circuit-id",
          "client-id"
        ],
        "hostname-char-replacement": "",
        "hostname-char-set": "[^A-Za-z0-9.-]",
        "interfaces-config": {
          "interfaces": [
            "enp0s8"
          ],
          "re-detect": true
        },
        "lease-database": {
          "type": "memfile"
        },
        "loggers": [
          {
            "name": "kea-dhcp4",
            "output_options": [
              {
                "output": "stdout"
              }
            ],
            "severity": "DEBUG"
          }
        ],
        "match-client-id": true,
        "multi-threading": {
          "enable-multi-threading": false,
          "packet-queue-size": 64,
          "thread-pool-size": 0
        },
        "next-server": "0.0.0.0",
        "option-data": [],
        "option-def": [],
        "reservation-mode": "all",
        "sanity-checks": {
          "lease-checks": "warn"
        },
        "server-hostname": "",
        "server-tag": "abc",
        "shared-networks": [],
        "statistic-default-sample-age": 0,
        "statistic-default-sample-count": 20,
        "store-extended-info": false,
        "subnet4": [],
        "t1-percent": 0.5,
        "t2-percent": 0.875,
        "valid-lifetime": 7200
      }
    },
    "result": 0
  }
]