Eyes are stretched horizontally when a project is build using cardboard SDK

Steps to reproduce:
1. Open attached project
2. File > Build Settings > Switch Platform to iOS
3. File > Build Settings > Player Settings > Other Settings > Use any graphics API
4. Build project and deploy on iOS device.

Reproducible on:
2018.3.0a7, 2018.3.0a3, 2018.3.0a2, 2018.2.0f2, 2018.2.0b9, 2018.2.0b1, 2018.1.0f2, 2017.3.0f3

Working on:
2017.2.0f3, 2017.1.0f3

Devices tested on:
iPhone 8 plus, iPhone 8 ,iPhone 7

Environment
Mac 10.13, 10.12

Note: Refer attached screenshot

Note: On 2018.3.0a7 this bug occurs with Metal API wehn device is in portrait mode. Works fine in landscape mode.

Note: This is an issue with the GVR SDK. That issue is tracked here:
https://github.com/googlevr/gvr-unity-sdk/issues/838