Steps to repro:

1. Open attached project and 't2' scene;
2. Enter Play mode;
3. Observe terrain surface rendering.

Expected reuslt:
Terrain is rendered smoothly without artifacts (see attached expected.png screenshot).

Actual result:
Sun flare artifact is shown on terrain surface (see attached actual.png screenshot).
Regression introduced in Unity 2017.2.0b2.

Notes:
- Reproducible in 2018.1.0a2, 2017.3.0b7, 2017.2.0b2;
- Not reproducible in 2017.2.0b1, 2017.1.0p4;
- Reproducible on Windows 10 and OSX 10.12.6;
- Also reproducible in Standalone player.