How to reproduce:
1. Open user's project
2. Go to Assets > Test, it should create material
The material in Project Explorer looks green like it has Emission enabled.
3. Select "TestMaterial" in Project Window.
In some versions, green color in Project Window disappears, in some, it doesn't, but Emission was not enabled.

Expected result: You can enable Emission through the code.
Actual result: You cannot enable Emission through the code.

Reproducible with - 2018.3.0a3, 2018.2.0b9, 2018.1.6f1, 2017.4.6f1, 2018.2.3p1, 2017.1.4p2