You should configure your CI to ignore PRs whose base branch is named graphite-base/*. Not doing so may result in failed CI jobs, specifically when they reference Graphite’s temporary branches which have been deleted. Here’s how to disable running CI for these branches in GitHub Actions: 
on:
  pull_request:
    types: [opened, reopened, synchronize]
    branches-ignore:
      - "**/graphite-base/**"
For more information about when and why these temporary branches get created, refer to Automatic rebasing.