Constraints w/ concave shapes not allowed but compound works

[toglia]

I was trying to apply a hinge constraint to a concave triangle mesh shape when I found out from the calculateLocalInertia method of the btTriangleMeshShape source file that bullet did not allow moving concave shapes.

This caught my attention cause previously I had successfully applied the same hinge constraint to a concave compound, (triangle concave shapes)

So what's the final verdict? How is that possible?