CI: refactor Squash and Merge with simplified branch merging (#726)

* Refactor squash and merge script for improved simplicity

Simplified the squash_and_merge.py script by replacing redundant utility functions and consolidating logic. Enhanced usability by aligning command-line arguments and leveraging streamlined git operations to improve maintainability and reliability.

* Fix argument names in squash PR script

Renamed CLI arguments from '--base' and '--source' to '--target' and '--base' to align with expected input format. This ensures the script runs correctly with proper argument mapping.

* Fix incorrect base branch argument in squash script

    Updated the `--base` argument to use `source_branch` instead of `branch` to ensure the squash script processes the correct base branch. Also adjusted the command to include `branch` as a separate argument for clarity and correctness.

* Reset to a clean state after squash error.

Add a `git reset --hard` command to ensure the repository returns to a clean state after encountering errors during the squash and merge process. This prevents lingering changes from affecting subsequent operations.

* Improve error handling in squash_and_merge_prs.py

Capture and display both stdout and stderr in error cases to provide more informative feedback. Adjust the PR comment to include available output for better debugging.

* Refactor PR squash process to enhance error handling.

Modify subprocess handling to use `result.returncode` for error checks instead of relying on exceptions. Consolidate error output retrieval and logging for better clarity, while maintaining the workflow for resetting changes on failure.

* Fix incorrect return in PR processing loop

Replaced `return` with `continue` to ensure all PRs in the loop are processed before exiting. This prevents premature termination of the function and ensures accurate success count reporting.

* Simplify subprocess output handling in squash_and_merge.py

Replaced labeled print statements with direct output of stdout and stderr. This change ensures cleaner logs and remains consistent with the function's purpose of output handling during subprocess execution.

* Update subprocess.run calls to use capture_output parameter

Replaced `stdout` and `stderr` with the `capture_output` parameter for cleaner and more concise subprocess handling. Also removed extraneous whitespace for improved code readability.

* testing moving the squash script given that it's called iteratively and switching branch might miss it

* format

---------

Co-authored-by: Jason Wen <haibin.wen3@gmail.com>

.github/workflows/sunnypilot-master-dev-c3-prep.yaml

@@ -36,7 +36,7 @@ jobs:
         run: |
           git config --global user.name 'github-actions[bot]'
           git config --global user.email 'github-actions[bot]@users.noreply.github.com'
-          
+
       - name: Set up SSH
         uses: webfactory/ssh-agent@v0.9.0
         with:
@@ -63,10 +63,10 @@ jobs:
             echo "Source branch ${{ inputs.source_branch || env.DEFAULT_SOURCE_BRANCH }} does not exist!"
             exit 1
           fi
-          
+
           # Make sure we have the latest source branch
           git fetch origin ${{ inputs.source_branch || env.DEFAULT_SOURCE_BRANCH }}
-          
+
           # Check if target branch exists
           if ! git ls-remote --heads origin ${{ inputs.target_branch || env.DEFAULT_TARGET_BRANCH }} | grep -q "${{ inputs.target_branch || env.DEFAULT_TARGET_BRANCH }}"; then
             echo "Target branch ${{ inputs.target_branch || env.DEFAULT_TARGET_BRANCH }} does not exist, creating it from ${{ inputs.source_branch || env.DEFAULT_SOURCE_BRANCH }}"
@@ -110,17 +110,19 @@ jobs:
                 }
               }
             }' -F label="is:pr is:open label:${PR_LABEL} sort:created-asc")
-          
+
           echo "PR_LIST=${PR_LIST}" >> $GITHUB_OUTPUT
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Process PRs
         run: |
+          cp ${{ github.workspace }}/release/ci/squash_and_merge.py /tmp/squash_and_merge.py && \
+          chmod +x /tmp/squash_and_merge.py && \
           python3 ${{ github.workspace }}/release/ci/squash_and_merge_prs.py \
             --pr-data '${{ steps.get-prs.outputs.PR_LIST }}' \
             --target-branch ${{ inputs.target_branch || env.DEFAULT_TARGET_BRANCH }} \
-            --squash-script-path '${{ github.workspace }}/release/ci/squash_and_merge.py'
+            --squash-script-path '/tmp/squash_and_merge.py'
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}