Mirroring a repo in an Action fails after update to latest checkout version

[hongooi73]

I have some repos in one organisation that, for historical reasons, are mirrored in another organisation. To do the mirroring, I have the following code setup as a GH action:

    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          fetch-depth: 0  # required for mirroring, see https://stackoverflow.com/a/64272409/474349

      - name: Copy to Cloudyr
        if: github.repository_owner == 'Azure' && runner.os == 'Linux' && github.ref == 'refs/heads/master'
        env:
          token: "${{ secrets.ghPat }}"
        # git config hack required, see https://stackoverflow.com/q/64270867/474349
        run: |
          export CLOUDYR_REPO=$(echo $GITHUB_REPOSITORY | sed "s/Azure/cloudyr/")
          git config -l | grep 'http\..*\.extraheader' | cut -d= -f1 | \
            xargs -L1 git config --unset-all
          git push --prune https://token:$token@github.com/${CLOUDYR_REPO}.git +refs/remotes/origin/*:refs/heads/* +refs/tags/*:refs/tags/*

... more steps ...

This copies the repo from the Azure org to Cloudyr, and worked perfectly for years. Yesterday the GH dependabot made a PR to update all the pinned version numbers to the latest (v7.0.1 for the checkout action, as seen above). Since then, the step has failed at this point:

Run export CLOUDYR_REPO=$(echo $GITHUB_REPOSITORY | sed "s/Azure/cloudyr/")
# [debug]/usr/bin/bash -e /home/runner/work/_temp/9163680c-38a6-43e6-8b4f-4f62fa2c4dcc.sh
Error: Process completed with exit code 123.

You can see the repo and full log here.

Does anyone know what's causing this problem, and how I can fix it?

[hongooi73]

After some poking around, it looks like 6.0.0 is where the breaking change is. My guess is that it's related to #2286