[HDRP] Materials of active assets turn black on changing the Color space from Linear to Gamma. Materials remain black even when Color space is switched back to Linear. User also doesn't get any warning when switching to Gamma. Refer attached screenshot.

Steps to reproduce:
1) Create new project > Select template HDRP
2) Player settings > Other settings > Change Color space to Gamma

Actual result: Observe that all assets become unlit.
Expected result: Scene should be properly rendered.

Occurs on : 2018.2.0b7, 2018.2.0b1, 2018.1.3f1, 2018.1.0b5
Environment : Windows and Mac

Workaround : Enter and exit play-mode or reload a scene.

Stack trace:
1) Graphics.CopyTexture could not find destination D3D11 texture object. Maybe it is a RenderTexture that is not created yet ?
2) Graphics.CopyTexture could not find source D3D11 texture object. Maybe it is a RenderTexture that is not created yet?
3) RenderTexture.GenerateMips failed: render texture is not rendered into yet, or does not have a color surface.
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)