Ctrl-Z clears all material nodes in scene

[Jgrover111]

System Information

Windows 10 Home (64-bit)
Intel Core i5-6200U

Software Version

• Blender version: 2.79a
• LuxCore version: Beta3 (No OpenCL)

Short description of error

When I press Ctrl-Z to undo something all of my material nodes get cleared and I have to recreate them all over again, which is really annoying as I seem to press it more often than I notice :?

Exact steps for others to reproduce the error

The error is not scene or context specific and nothing specific is needed to reproduce it.
Just create a new scene, create a material out of nodes for the default cube using the node tree preset buttons, move the cube and press Ctrl-Z so the cube snaps back to the original position, but the material nodes will disappear

[Jgrover111]

Tested in 2.79b and still happens

[Jgrover111]

Demonstration in 2.79b:
2018-04-18 08-58-30.zip

[Theverat]

You can just attach files here to this issue (might have to zip it).

I can now reproduce the problem. It only happens when you use the node tree preset buttons (I always clicked new material). I'll look into it.