migration "MoveStylesToContent" fails+discussion

Hi Brett,

Sorry for the slow reply; I was away for Thanksgiving.

Your diagnosis is exactly correct. There is a new validation of codename uniqueness that mishandling nil codenames. I've just added a fix and will try to get that pushed and deployed soon, but you shouldn't need it. Your workaround looks fine to me (though of course you're right: most wouldn't be able -- and shouldn't need -- to figure that out!).