When I open a pull request, I have a github action set to trigger a node script:

name: Check i18n tokens 🇮🇹
on:
    pull_request:
        types: [labeled, unlabeled, opened, synchronize, reopened]
        branches: ['master']
jobs:
    check-I18N-tokens:
        needs: generate-matrix
        # A check job is performed for each element present in needs.generate-matrix.outputs.matrix. If empty ([]), the job is skipped.
        if: ${{ !contains(needs.generate-matrix.outputs.matrix, '[]') }}
        strategy:
            matrix: ${{ fromJSON(needs.generate-matrix.outputs.matrix) }}
        runs-on: [self-hosted, cdorunner-life-novum, Linux]
        container: xxx
        steps:
            - name: checkout
              uses: actions/checkout@v4
            - name: Install dependencies
              run: yarn
            - name: Performing the check
              run: yarn perform list-files-changed
...

Where the script performs something like the following:

const currentBranch = execSync('git rev-parse --abbrev-ref HEAD', {encoding: 'utf8'}).trim();
const diffFilesOutput = execSync(`git diff --name-only $(git merge-base ${currentBranch} master)`, {
    encoding: 'utf8',
});
const filesToCheck = diffFilesOutput.split(/r?n/).filter((file) => file.endsWith('.tsx'));
console.log(filesToCheck);

now, it used to work on github actions, but now I got the following:

fatal: Not a valid object name master

so I’m here asking: is there a way to diff the PR against master, without checking out the whole repo? it’s huge and it’d save a lot of resources (and time)

Update

I’ve found a discussion that could be related to this: github checkout discussion