UI does not send interface constraints when composing a machine

[amylily1011]

I tried to compose a machine with two interfaces using the UI. The request went through with no errors however the region never received any interface constraints. Below is what was sent over the websocket. As you can see "interfaces" is set to ""

Note this effects all Pod types and this bug may exist previous versions of MAAS.

{
"type": 0,
"request_id": 24,
"method": "pod.compose",
"params": {
"storage": "0:4(maas),1:4(maas)",
"requests": [
{
"poolId": "e9c55659-125f-4b50-abf7-7ed631b3602c",
"size": 8,
"available": 11
}
],
"interfaces": "",
"domain": 0,
"zone": 1,
"cores": "2",
"memory": "2048",
"id": 78
}
}

https://bugs.launchpad.net/maas/+bug/1876180