traefik: traefik doesn't respect kubernetes.io/ingress.class

traefik: 1.1.2 kubernetes: 1.5.2 OS: ubuntu 14.04

Test kubernetes deployment, service, ingress:

apiVersion: v1
kind: Service
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: nginx
  type: ClusterIP

---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80

---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: nginx
  annotations:
    kubernetes.io/ingress.class: "nginx"
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path:
        backend:
          serviceName: nginx
          servicePort: 80

Important: There is metadata.annotations: kubernetes.io/ingress.class: "nginx" in ingress.

Instead of skip this ingress (kubernetes.io/ingress.class: "nginx") traefik is processing it and adding frontend and backend:

# curl -s 127.0.01:8080/api | jq '.kubernetes.frontends["example"]'
{
  "priority": 0,
  "passHostHeader": true,
  "routes": {
    "example.com": {
      "rule": "Host:example.com"
    }
  },
  "backend": "example.com",
  "entryPoints": [
    "http"
  ]
}

# curl -s 127.0.0.1:8080/api | jq '.kubernetes.backends["example.com"]'
{
  "loadBalancer": {
    "method": "wrr"
  },
  "servers": {
    "nginx-1691775941-kpx47": {
      "weight": 0,
      "url": "http://10.200.70.23:80"
    }
  }
}

Traefik should ship this ingress because of kubernetes.io/ingress.class: "nginx".