• Extension version: v0.12.0
• VSCode Version: 1.40.0-insider
• OS: osx

Steps to Reproduce:

1. Open a pull request
2. Checkout the source code using Description page
3. Open a file with added line

expectation:
I would see the white gutter to be able to comments

reality:
The white gutter was not shown. See below on the right side

This doesn't happens if i view the file using the "Github Pull Requests" section (branch not checked out)

see #1339 (comment) for extra details