Grab pass + VR is Broken

I'm trying to update my project from Unity 5.5.4p4 to Unity 2017.2.0b11 (I need this to target Windows MR)
I'm stuck with a problem with some shaders that use Grab pass.
To illustrate the problem I've created this simple project.
It includes the SteamVR 1.2.2 plugin.
In the scene I have the SteamVR Camera Rig prefab, some cubes and a Plane that has a material with the following shader on it (that I've created with Shader Forge):

Code (CSharp):

1. Shader "Shader Forge/test" {
2.     Properties {
3.     }
4.     SubShader {
5.         Tags {
6.             "IgnoreProjector"="True"
7.             "Queue"="Transparent"
8.             "RenderType"="Transparent"
9.         }
10.         GrabPass{ }
11.         Pass {
12.             Name "FORWARD"
13.             Tags {
14.                 "LightMode"="ForwardBase"
15.             }
16.             ZWrite Off
17.            
18.             CGPROGRAM
19.             #pragma vertex vert
20.             #pragma fragment frag
21.             #define UNITY_PASS_FORWARDBASE
22.             #include "UnityCG.cginc"
23.             #pragma multi_compile_fwdbase
24.             #pragma only_renderers d3d9 d3d11 glcore gles
25.             #pragma target 3.0
26.             uniform sampler2D _GrabTexture;
27.             struct VertexInput {
28.                 float4 vertex : POSITION;
29.                 float2 texcoord0 : TEXCOORD0;
30.             };
31.             struct VertexOutput {
32.                 float4 pos : SV_POSITION;
33.                 float2 uv0 : TEXCOORD0;
34.                 float4 projPos : TEXCOORD1;
35.             };
36.             VertexOutput vert (VertexInput v) {
37.                 VertexOutput o = (VertexOutput)0;
38.                 o.uv0 = v.texcoord0;
39.                 o.pos = UnityObjectToClipPos( v.vertex );
40.                 o.projPos = ComputeScreenPos (o.pos);
41.                 COMPUTE_EYEDEPTH(o.projPos.z);
42.                 return o;
43.             }
44.             float4 frag(VertexOutput i) : COLOR {
45.                 float2 sceneUVs = (i.projPos.xy / i.projPos.w);
46.                 float4 sceneColor = tex2D(_GrabTexture, sceneUVs);
47. ////// Lighting:
48. ////// Emissive:
49.                 float3 emissive = tex2D( _GrabTexture, i.uv0).rgb;
50.                 float3 finalColor = emissive;
51.                 return fixed4(finalColor,1);
52.             }
53.             ENDCG
54.         }
55.     }
56.     FallBack "Diffuse"
57.     CustomEditor "ShaderForgeMaterialInspector"
58. }
59.  

Running this project on Unity 5.5.4p4 I see this view of the Plane in the game viewport:


Running the same project on Unity 2017.2.0b11 gives me this view:


As you can see, in 2017 we only see one eye (with some black bars) instead of both eyes.

 

I already did, here is the case number:
Case 953360