1) creating a broadphase proxy -> adding pairs during insertion. But during this pair insertion, the btGhostObject broadphase handle isn't set yet (it is done in step 2)
2) assign the broadphase proxy to btGhostObject
Thanks to ihar3d for the report http://bulletphysics.com/Bullet/phpBB3/viewtopic.php?f=9&t=2864