The finish to CM Punk and Brock Lesnars' SummerSlam match was changed just days before the event, reports The Wrestling Observer. The reason for the change might be due to The Undertaker agreeing to work Lesnar at next year's WrestleMania in New Orleans.
Lesnar's contract is said to include three pay per view matches per year, including WrestleMania, meaning he's likely done until next year's mega-event in New Orleans (he's worked Mania 29, Extreme Rules, and now SummerSlam). However, even with the extended time off between SummerSlam and Mania next year, WWE officials didn't want him heading into that high-profiled match with Taker holding a 2-3 record (since his return).
While Taker/Lesnar isn't confirmed for WrestleMania 30, it's looking more and more likely each month.