Fix compatibility with actions/checkout@v6

[ericsciple]

Temporarily hides checkout@v6 credential files to prevent duplicate Authorization headers.

Fixes issue:

• Incompatible with actions/checkout@v6 #4228

Solution approach:

• Backup $RUNNER_TEMP/git-credentials-*.config files before configuring auth
• Configure action's auth in .git/config as normal
• Restore credential files on cleanup

This avoids the duplicate header error while properly preserving and restoring checkout's credentials for use in subsequent workflow steps.

[ericsciple]

Tested E2E here:

• https://github.com/ericsciple/create-pull-request/actions/runs/19592107407

Workflow YAML

jobs:
  test-checkout-v6:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout with v6
        uses: actions/checkout@v6

      - name: Make a test change
        run: |
          echo "Test change at $(date)" >> test-file.txt
          echo "This tests checkout@v6 compatibility"

      - name: Create Pull Request
        uses: ./
        with:
          token: ${{ secrets.GITHUB_TOKEN }}
          commit-message: 'test: checkout@v6 compatibility test'
          title: 'Test: checkout@v6 compatibility'
          body: |
            Automated test of checkout@v6 compatibility fix
            
            This PR tests that create-pull-request works correctly with actions/checkout@v6
          branch: test/checkout-v6-compat
          delete-branch: true

  test-checkout-v5:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout with v5
        uses: actions/checkout@v5

      - name: Make a test change
        run: |
          echo "Test change at $(date)" >> test-file-v5.txt
          echo "This tests backward compatibility with checkout@v5"

      - name: Create Pull Request
        uses: ./
        with:
          token: ${{ secrets.GITHUB_TOKEN }}
          commit-message: 'test: checkout@v5 backward compatibility test'
          title: 'Test: checkout@v5 compatibility'
          body: |
            Automated test of checkout@v5 backward compatibility
            
            This PR verifies that the fix doesn't break checkout@v5 workflows
          branch: test/checkout-v5-compat
          delete-branch: true

[peter-evans]

/test repository=ericsciple/create-pull-request ref=users/ericsciple/25-11-creds build=true

Command run output

[peter-evans]

/test repository=ericsciple/create-pull-request ref=users/ericsciple/25-11-creds

Command run output

[peter-evans]

@ericsciple Thank you for raising this fix! Very much appreciated. ❤️

I'll take a look at what changed in v6 at some point to see if there is anything I should do differently.

[anagyzambo-kx]

@ericsciple Thank you for raising this fix! Very much appreciated. ❤️

I'll take a look at what changed in v6 at some point to see if there is anything I should do differently.

I guess the getAndUnset() used to hide the extraheader credentials:

  /usr/bin/git config --local --get-regexp http.https://github.com/.extraheader ^AUTHORIZATION:
  http.https://github.com/.extraheader AUTHORIZATION: basic ***
  /usr/bin/git config --local --unset http.https://github.com/.extraheader ^AUTHORIZATION:
  Unset config key 'http.https://github.com/.extraheader'

But credentials have been refactored in actions/checkout@v6:
Persist creds to a separate file #2286