ScaleIO: use a fresh mounter for every SetUp/TearDown

A volume plugin should not cache Mounter for a long time, it can get a
different one with each SetUp/TearDown call.

pkg/volume/scaleio/sio_volume_test.go

@@ -30,7 +30,6 @@ import (
 	"k8s.io/apimachinery/pkg/types"
 	fakeclient "k8s.io/client-go/kubernetes/fake"
 	utiltesting "k8s.io/client-go/util/testing"
-	"k8s.io/kubernetes/pkg/util/mount"
 	"k8s.io/kubernetes/pkg/volume"
 	volumetest "k8s.io/kubernetes/pkg/volume/testing"
 )
@@ -138,8 +137,6 @@ func TestVolumeMounterUnmounter(t *testing.T) {
 		t.Errorf("Cannot assert plugin to be type sioPlugin")
 	}
 
-	sioPlug.mounter = &mount.FakeMounter{}
-
 	vol := &api.Volume{
 		Name: testSioVolName,
 		VolumeSource: api.VolumeSource{