title: volumeMount subPath doesn't work
body: <p>I'm trying to make use of the new <code>subPath</code> feature implemented in <a href="https://github.com/kubernetes/kubernetes/pull/22575" rel="noreferrer">this</a> pull request (recently released in v1.3).</p>
  
  <p>However, the output of <code>mount</code> shows it ignoring the <code>subPath</code>, mounting the same NFS directory for both volume mounts:</p>
  
  <pre><code>nfs-server:/mnt/nfs/exports/apps/my-app on /home/share/foo type nfs4 (rw,relatime,vers=4.0,rsize=524288,wsize=524288,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=10.128.0.4,local_lock=none,addr=nfs-server)
  nfs-server:/mnt/nfs/exports/apps/my-app on /home/share/bar/baz type nfs4 (rw,relatime,vers=4.0,rsize=524288,wsize=524288,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=10.128.0.4,local_lock=none,addr=nfs-server)
  </code></pre>
  
  <p>The relevant bits of my deployment YAML:</p>
  
  <pre><code>apiVersion: extensions/v1beta1
  kind: Deployment
  metadata:
    name: app
  spec:
    replicas: 1
    template:
      metadata:
        labels:
          name: app
      spec:
        containers:
        - name: app
          image: my-org/my-app:latest
          volumeMounts:
          - mountPath: /home/share/foo
            name: nfs
            subPath: foo-resources
          - mountPath: /home/share/bar/baz
            name: nfs
            subPath: baz-resources
        volumes:
        - name: nfs
          nfs:
            path: /mnt/nfs/exports/apps/my-app
            server: nfs-server
  </code></pre>