System Information
Operating system and graphics card
Blender Version
2.72b 9e963ae
Short description of error
when enter in edit mode of an object, then in local view ( and this is important because if not the bug doesn't happens) add a greace pencil trace an try to make a bsurfaces it brokens.
Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps
