BUG FIX: Ensure Build Title Is Correct When Checkout Is Skipped

[123sarahj123]

Description

Bug: When using skip-checkout plugin, the build title and commit details will match the previously checked out commit details (rather than taking it from the webhook details).

See video below. I trigger a build via webhook (with skip checkout). It starts off with the correct details, but changes to to the details of HEAD

Screen.Recording.2024-10-04.at.1.00.33.PM.mov

Changes

Ensure agent gets correct commit message associated with webhook-triggered build, rather than reading it from git repo's HEAD.

Modified function sendCommitToBuildkite in internal/job/checkout.go to extract the message from e.Commit rather than HEAD

Testing / Reproduction

To reproduce bug

• Set up a pipeline (or use an existing one).
• Ensure a webhook triggers the build on push events (when you push to a branch, it triggers a build).
• Run a build that performs a checkout so there is a working directory with older commit details.
• Now add a step to your pipeline.yml to use the skip-checkout plugin. For example:

steps:
  - label: "Skip checkout step"
    command: "echo 'Skipping checkout and returning true'"
    plugins:
      - thedyrt/skip-checkout#v0.1.1: ~

• Push a new commit and trigger the build via the webhook.

• Observe the build logs. You'll notice the build takes commit details from the old commit (due to skipping checkout) instead of the new one.

• Tests have run locally (with go test ./...). Buildkite employees may check this if the pipeline has run automatically.

• Code is formatted (with go fmt ./...)

[patrobinson]

This seems pretty reasonable

[DrJosh9000]

LGTM

I'm happy this does what it says, and having thought about it, I'm happy that making the build title always reflect the commit rather than whatever HEAD is in the repo is a reasonable approach.