Shader error in 'VolumetricLighting' error on updating HDRP package from 9.0.0-preview.33 to 9.0.0-preview.54.

Steps to repro:
1. Create a new HDRP project.
2. Windows > Package Manager > HDRP > Update to 9.0.0-preview.33.
3. Windows > Package Manager > HDRP > Update to 9.0.0-preview.54.

Actual Result:
Shader error in the console.

Expected Result:
No errors in the console.

Reproducible in:
2020.2.0b2, 2020.1.5f1, 2020.1.0b13.

Note: Scene Template is available from 2020.2.0a15.

Environment:
Occurring on Windows 10 & Mac 10.15.

Stacktrace:
Asset Packages/com.unity.shadergraph/ValidationConfig.json has no meta file, but it's in an immutable folder. The asset will be ignored.

Shader error in 'VolumetricLighting': failed to open source file: 'Packages/com.unity.render-pipelines.high-definition/Runtime/Lighting/VolumetricLighting/VolumetricLighting.cs.hlsl' at kernel VolumetricLighting at VolumetricLighting.compute(54) (on d3d11)