Permission denied creating tar for Apt files

Based on @joshmgross's latest comment in https://github.com/actions/cache/issues/133#issuecomment-629381394, here's my use case, same as @evandrocoan https://github.com/actions/cache/issues/133#issuecomment-602695437...

caching Apt list and package files in Ubuntu

Example workflow

The Apt step here takes about 35 seconds without caching. I'm hoping the cache will improve that. I'm also not 100% sure about the paths because I haven't been able to test it yet.

      - name: Use Apt lists cache
        uses: actions/cache@v1
        with:
          path: /var/lib/apt/lists
          key: ${{ runner.os }}-apt-lists
      - name: Use Apt packages cache
        uses: actions/cache@v1
        with:
          path: /var/cache/apt
          key: ${{ runner.os }}-apt-packages
      - name: Install Apt dependencies
        run: |
          sudo apt-get update
          sudo apt-get install -y liblua5.1-dev luarocks

Error during post job

Post job cleanup.
/bin/tar -cz -f /home/runner/work/_temp/207e89c2-b0e5-4443-915a-2eafc37bc59b/cache.tgz -C /var/cache/apt .
/bin/tar: ./archives/partial: Cannot open: Permission denied
/bin/tar: ./archives/lock: Cannot open: Permission denied
/bin/tar: Exiting with failure status due to previous errors
[warning]Tar failed with error: The process '/bin/tar' failed with exit code 2