Updates lease creation to respect existing leases

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

task.go

@@ -18,7 +18,6 @@ import (
 	"github.com/containerd/containerd/diff"
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
-	"github.com/containerd/containerd/leases"
 	"github.com/containerd/containerd/mount"
 	"github.com/containerd/containerd/plugin"
 	"github.com/containerd/containerd/rootfs"
@@ -358,13 +357,11 @@ func (t *task) Resize(ctx context.Context, w, h uint32) error {
 }
 
 func (t *task) Checkpoint(ctx context.Context, opts ...CheckpointTaskOpts) (Image, error) {
-	l, err := t.client.CreateLease(ctx)
+	ctx, done, err := t.client.withLease(ctx)
 	if err != nil {
 		return nil, err
 	}
-	defer l.Delete(ctx)
-
-	ctx = leases.WithLease(ctx, l.ID())
+	defer done()
 
 	request := &tasks.CheckpointTaskRequest{
 		ContainerID: t.id,