`kpt pkg diff` doesn't show host paths

[frankfarzan]

$ cd /tmp/hello-world-workspace
$ kpt pkg diff
diff /var/folders/yw/dmxc0tlx7td3n1mjpwlq21yr0048dv/T/kpt-941888986/deploy.yaml /var/folders/yw/dmxc0tlx7td3n1mjpwlq21yr0048dv/T/kpt-571299697/deploy.yaml
21c21
<     app: hello1
---
>     app: hello