Broken: latest buildbot
Short description of error
If you join 2 2D curves that have different height, they will keep their height. Only setting to 3D then back to 2D will make them really 2D. Expected is that all joined curve go to the active curve height.
If one of the joined curve was 3D, it will stay 3D although the option is set to 2D in the active curve (see layer 2 in attached file).
Exact steps for others to reproduce the error
Open attached file. Hit ctrl+J to join, both curve stay where they are. Now select 3D in the curve parameters and then back to 2D, it is now correct.
Go to layer 2, you have a 2D curve with a curve that you can move along Z !