Why tweet_status_id_str on EntryVersion and not Diff?

[edsu]

Since diffs are tweeted and not particular versions I'm wondering why we are storing the tweet id for the diff on the EntryVersion instead of Diff? I think it would be cleaner to store it on the Diff right?

[nahuelhds]

This was done this way for easy threading. I asked the same myself and I even try go that path but implied a little rework that I didn't want to face on that stage.