Thought so. This means that we won’t be able to update to Bullet 2.81 on the release branch, because the Bullet API changed const-ness of some objects from 2.80 to 2.81 (non-const to const), and we need to follow in our wrappers. This is unfortunate, because there have been important bug fixes in Bullet 2.81.
Hmm… is there a way to check ABI compatibility BEFORE check in to the release branch (I’m using Win7/VS2010 Express/Win7 SDK, and currently don’t have any Linux virtual machines set up)? If not I would prefer to build a patch file and send it to you via mail.