[2.0a4] duplicate ipranges cuase dhcpd Configuration file errors

[John George]

Duplicate iprange entries were added with:
    'maas _maas ipranges create type=dynamic start_ip=10.245.208.150 end_ip=10.245.208.250'

[
    {
        "comment": "",
        "end_ip": "10.245.208.250",
        "start_ip": "10.245.208.150",
        "id": 1,
        "subnet": {
            "dns_servers": [],
            "name": "10.245.208.0/20",
            "gateway_ip": "10.245.208.5",
            "space": "space-0",
            "cidr": "10.245.208.0/20",
            "resource_uri": "/MAAS/api/2.0/subnets/1/",
            "vlan": {
                "fabric": "fabric-0",
                "primary_rack": "4y3h7n",
                "dhcp_on": true,
                "id": 1,
                "name": "untagged",
                "secondary_rack": null,
                "mtu": 1500,
                "resource_uri": "/MAAS/api/2.0/vlans/1/",
                "vid": 0
            },
            "rdns_mode": 2,
            "id": 1
        },
        "resource_uri": "/MAAS/api/2.0/ipranges/1/",
        "type": "dynamic",
        "user": {
            "username": "root",
            "email": "ubuntu@localhost",
            "is_superuser": true
        }
    },
    {
        "comment": "",
        "end_ip": "10.245.208.250",
        "start_ip": "10.245.208.150",
        "id": 2,
        "subnet": {
            "dns_servers": [],
            "name": "10.245.208.0/20",
            "gateway_ip": "10.245.208.5",
            "space": "space-0",
            "cidr": "10.245.208.0/20",
            "resource_uri": "/MAAS/api/2.0/subnets/1/",
            "vlan": {
                "fabric": "fabric-0",
                "primary_rack": "4y3h7n",
                "dhcp_on": true,
                "id": 1,
                "name": "untagged",
                "secondary_rack": null,
                "mtu": 1500,
                "resource_uri": "/MAAS/api/2.0/vlans/1/",
                "vid": 0
            },
            "rdns_mode": 2,
            "id": 1
        },
        "resource_uri": "/MAAS/api/2.0/ipranges/2/",
        "type": "dynamic",
        "user": {
            "username": "root",
            "email": "ubuntu@localhost",
            "is_superuser": true
        }
    },
]

Subsequently MAAS added duplicate entries to /var/lib/maas/dhcpd.conf and dhcpd failed to start.