System Information
Operating system and graphics card
Windows 10, GTX 870

Blender Version
Broken: (example: 2.69.7 4b206af, see splash screen)
Worked: (optional)
Blender 2.78a and 2.73a

Short description of error
Blender 2.78, Exporting FBX creating extra bone. Bone is from the Armature object. This was reported in T45368.

Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps

I have a model from Neverwinter Night, bones and animation were imported from SMD. Everything looks fine, mesh, bones and animation, scaling was done to match mesh, vertexes autoweighted. Export FBX for import to 3ds Max, seeing extra bone. Renaming Armature object, Armature properties and root bone shows it come from the Armature object. Export is 6.1 ascii, same result with Blender 2.73. It was stated that it may be Max but looking at the FBX file shows it's in the file. Export should only have original bones, in this case the root bone has to be named c_chicken_skel. Trying to delete the extra bone messes up the animation frames, frames must be tied to the new bone.