I'm not sure that block is really an XT block. It was mined by Slush pool, which is still creating all version 3 blocks. That particular block has a bizarre version field for some reason.
It is an XT block. Sadly.
Version: 536870919(10) = 0x20000007 (hex)
Edit: Sorry, someone on reddit said that, not Slush. https://www.reddit.com/r/bitcoinxt/comments/3hhbm5/first_mined_xt_block_370434/