Fix single-commit check for stable branch PRs

[zjhuntin]

Summary

The single-commit workflow added in #1032 enforces one commit per PR to ensure squashed commits before merging. However, it was hardcoded to compare against develop, which breaks for PRs targeting stable branches like foreman_3_18.

This change uses github.base_ref to dynamically compare against the PR's actual target branch.

Problem

PRs like #1166 (Release 13.2.3) targeting foreman_3_18 fail the commit count check because the stable branch has diverged from develop.

Solution

Replace hardcoded develop with ${{ github.base_ref }} so the check works for PRs targeting any branch.

Summary by Sourcery

CI:

• Adjust the single-commit check workflow to fetch and create a local branch from github.base_ref and use it as the reference for the commit count check.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Updates the single-commit GitHub Actions workflow to compare commits against the PR’s actual base branch instead of hardcoding the develop branch, so the single-commit check works for PRs to any branch, including stable branches.

Sequence diagram for updated single-commit GitHub Actions workflow

sequenceDiagram
    actor Developer
    participant GitHub
    participant SingleCommitWorkflow
    participant ActionsCheckout
    participant GitCLI

    Developer->>GitHub: Open pull_request (head -> base_branch)
    GitHub-->>SingleCommitWorkflow: Trigger workflow on pull_request

    SingleCommitWorkflow->>ActionsCheckout: Checkout current HEAD (PR branch)
    ActionsCheckout-->>SingleCommitWorkflow: Working copy at HEAD

    SingleCommitWorkflow->>GitCLI: git fetch origin github.base_ref
    GitCLI-->>SingleCommitWorkflow: Fetched base branch refs

    SingleCommitWorkflow->>GitCLI: git branch base_branch origin/github.base_ref
    GitCLI-->>SingleCommitWorkflow: Local base_branch created

    SingleCommitWorkflow->>GitCLI: git log --oneline --no-merges HEAD ^base_branch
    GitCLI-->>SingleCommitWorkflow: Commit list between HEAD and base_branch

    SingleCommitWorkflow->>SingleCommitWorkflow: Count commits and compare to 1
    SingleCommitWorkflow-->>GitHub: Report success or failure
    GitHub-->>Developer: Show status of single-commit check

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Flow diagram for updated single-commit job steps

flowchart TD
    A[Start single-commit job] --> B[Checkout PR HEAD with actions/checkout]
    B --> C[Fetch origin github.base_ref]
    C --> D[Create local base_branch from origin/github.base_ref]
    D --> E[Run git log --oneline --no-merges HEAD ^base_branch]
    E --> F[Count commits between HEAD and base_branch]
    F --> G{Commit count == 1}
    G -- Yes --> H[Job succeeds]
    G -- No --> I[Job fails]
    H --> J[End]
    I --> J[End]

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File-Level Changes

Change	Details	Files
Make the single-commit workflow dynamically use the PR’s base branch rather than the hardcoded develop branch.	Change the fetch step to fetch the remote base branch referenced by github.base_ref instead of develop. Create a local branch named base_branch that tracks origin/${{ github.base_ref }} instead of a local develop branch. Update the commit count logic to compare HEAD against the new base branch rather than the develop branch (note that the final run command in the diff appears truncated and should be verified in the PR).	.github/workflows/single-commit.yml

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[sourcery-ai]

Hey - I've left some high level feedback:

• The commit count check still references develop; it should be updated to compare against the newly created base_branch (e.g., git log --oneline --no-merges HEAD ^base_branch).
• Consider quoting ${{ github.base_ref }} in the git fetch command to avoid issues if the branch name ever contains characters interpreted by the shell (e.g., git fetch origin "${{ github.base_ref }}").

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The commit count check still references `develop`; it should be updated to compare against the newly created `base_branch` (e.g., `git log --oneline --no-merges HEAD ^base_branch`).
- Consider quoting `${{ github.base_ref }}` in the `git fetch` command to avoid issues if the branch name ever contains characters interpreted by the shell (e.g., `git fetch origin "${{ github.base_ref }}"`).

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[jeremylenz]

Awesome, thanks @zjhuntin!

Seems https://github.com/Katello/katello/blob/master/.github/workflows/pull_request.yml will need the same fix.