Steps to reproduce

1. select a jetpack site, make sure you're logged in there
2. go to edit a blog post, make a change but don't save it
3. click the "View" button (what's "Preview" on non-JP sites)

What I expected

either opens new tab with a preview of the changed post, or doesn't do a preview and just shows me the post as it is (with the button reflecting which one is going to happen)

What happened instead

opens new tab, but jetpack site gives me a message like "Sorry, you are not allowed to preview drafts."