Environment lighting not working for Deferred render path in SF 1.38 in Unity 2017.3.1

To reproduce:

1) Make a simple deferred shader in Shader Forge

2) Make sure Unity is using the Deferred path under all the tiers in the Graphics settings

3) Make a material and drag it on an object

It won't use environment lighting.

Cube on the left uses a forward shader, which does work and shows how it should look. Cube on the right uses the deferred shader.