Not just the DUP, the HoL amendments were voted down in the Commons by 357-268 last night, so with 10 DUP MPs I'm guessing 347 Tories voted in favour just to see them given away less than 24 hours later. The controversial sections of the Bill were essentially a bargaining ploy by the UK government, an obvious deal-breaker for the EU and BJ ditching them means we're going to sign something in the next few days (famous last words).
Not that it bothers me much but the 357 who voted the amendments down last night must be feeling pretty foolish today!