System Information
win7 64 gtx970

Blender Version
Broken: 2.77 git.4b0aeaf

Short description of error
Blender internal material support stencil to mask textures, the only kind of texture that does not support this feature properly is the normal map channel.

Exact steps for others to reproduce the error
open the file and check.

ps: I reported this bug because I use Blender Internal to bulid end export materials to external render engine via FBX, having a correct preview would be a life saver.

thankyou!