When you walk over a tripwire or otherwise trigger a command block to /tp you, the command block completely ignores you (and instead picks the next player when using @p).
I'm not sure if this is INTENDED, but it'd be nice if it teleported you on your pig.
Duplicate of MC-16 , please use the search function to see if your bug has already been submitted. Currently over 30% of tickets are being closed as duplicate.