You need to be upgraded to the newest P2Pool version (v15.0, to support v4 blocks/BIP65) and then also make that change (if you want to support Bitcoin XT).
yes i have p2pool v 15.0.1, but this work?:
https://github.com/p2pool/p2pool/blob/master/p2pool/work.py - version=min(self.current_work.value['version'], 4),
+ version=536870919,