Bones rotated ~160° flip normals of normal maps

I’ve reported a bug a while ago about this:
Bones that are facing roughly 160 degrees from their original orientation (in world space) suddenly flip the normals of normal maps in the faces they influence.

does anyone have a workaround in the meantime? or suggestions? .blend is attached to the bug report.

I had that problem too on my windows PC, but not on my linux. I doubt that the OS has much to do with it, so I think it might be a graphics card related problem.

i have a gtx580 with recent drivers.
thing is that this only happens in game mode, not in normal glsl viewport shading, so i thought it might have to do with how the armature or mesh deform is being handled.
I had a gtx280 before and didnt encounter that problem, but i can’t test because the card broke.

I have run tests on 2 more windows machines with 2 different AMD graphics cards. The problem is the same.

I have attached the test files if anyone wants to check


normalmapBug.blend (704 KB)