Duplicate L3 Endpoints when reparenting L3 context

Keith found this with his testing. When testing L3 external networks, we get duplicate entries for the same L3 endpoint:

{
"l3-context": "ca765eeb-d68b-43c2-a5d2-8c8a8205d95f",
"ip-address": "192.168.111.70",
"endpoint-groups": [
"eeeaa3a2-e9ba-44e0-a462-bea923d30e38",
"1118172e-cd84-4933-a35f-749f9a651de9"
],
"tenant": "9aa70d61-6333-4e17-a5da-ac897dd3a292",
"ofoverlay:location-type": "external",
"timestamp": 1434505261750,
"network-containment": "410d34ee-7edd-4106-96c1-7b2ffe872005"
},
{
"l3-context": "897e9cc3-1eeb-43e1-81a6-128d703855d6",
"ip-address": "192.168.111.70",
"endpoint-groups": [
"eeeaa3a2-e9ba-44e0-a462-bea923d30e38",
"1118172e-cd84-4933-a35f-749f9a651de9"
],
"tenant": "9aa70d61-6333-4e17-a5da-ac897dd3a292",
"ofoverlay:location-type": "external",
"timestamp": 1434505263620,
"network-containment": "410d34ee-7edd-4106-96c1-7b2ffe872005"
},