Operating system: W10
Graphics card: GTX 1080TI
Worked: 2.79 master build
Short description of error
If you ctrl+a and press "visual geometry to mesh" on a curve that has a curve modifier, the resulting mesh you're getting is as if you didn't have that curve modifier at all. This was not the behaviour in 2.79b. Also, if you assign any constraints or assign this curve as a modifier for objects, you'll have it deformed as if the deforming curve doesn't have the curve modifier.
Exact steps for others to reproduce the error
Ctrl+a on the bezier curve in this sample file