[ISSUE-18] Customize cherry pick branch name

[lampajr]

Fix #18

So that users can have control over the new cherry-pick branch name, like re-using the original branch name concatenaed with the target one:

    steps:
      - name: Calculate release branch
        run: |
          label=${{ matrix.name }}
          echo "RELEASE_BRANCH=release/v1" >> $GITHUB_ENV
      - name: Checkout
        uses: actions/checkout@v3
        with:
          fetch-depth: 0
      - name: Perform cherry-pick
        uses: lampajr/github-cherry-pick-action@issue-18_cp_branch_name
        with:
          branch: "${{ env.RELEASE_BRANCH }}"
          title: "[${{ env.RELEASE_BRANCH }}] ${{ github.event.pull_request.title }}"
          body: "cherry-pick: ${{ github.event.pull_request.html_url }}"
          inherit_labels: false
          reviewers: |
            ${{ github.event.pull_request.user.login }}
          cherry-pick-branch: "${{ github.event.pull_request.head.ref }}_${{ env.RELEASE_BRANCH }}"

In this way users can cherry-pick the same change on more than one release branch or simply using their branching convention.

Note: In addition I also added some simple mocked tests that I used to validate the fix itself, I would include them too but if you don't agree I can remove them as well.

[lampajr]

I tried this fix in a custom repo.

Workflow config: https://github.com/lampajr/chain-status-example/blob/main/.github/workflows/backport.yaml

Generated cherry pick PRs:

• Using default branch name: [develop] Fix generate-status-page-data workflow step name lampajr/chain-status-example#4
• Customizing cherry pick branch name: [develop] Fix generate-status-page step name lampajr/chain-status-example#6

[lampajr]

Hi @carloscastrojumo whenever you get time could you please code review this?

[carloscastrojumo]

Hi @lampajr . Thank you for your contribution, specially for the new suite of tests.

I'm ok with override the cherry-pick branch name, I'm just curious, and this is more related to the actual #18, in what scenarios is this an issue? Release branch + git commit SHA should always be unique or what am I missing?

[lampajr]

Hi @carloscastrojumo , you are right that's not an issue as I completely missed the inputs.branch in the prBranch creation, my bad sorry.

On the other hand, just to give you more context on why I need this change: we are actually using build-chain to perform cross-repositories projects builds - this tool relies on the branch name in order to cross check multiple PRs on different repos, therefore we must ensure that multiple PRs (on different repos, that's the crucial point) share the same branch name (which cannot be ensured if using commit sha as part of the branch name itself).

If you want I can create a new issue with this motivation and link it to this PR, wdyt?

[carloscastrojumo]

It's fine. I will question the issue owner to see how can I help.

Thanks again for contributing.

[lampajr]

Thank you very much @carloscastrojumo