Distinguish commit vs merge commit in Push Events webhooks payload

maybe change objectKind to "mergePush" ?

As a user that is aiming to integrate an external system with GitLab, I would like to receive a webhook and have GitLab provide to me via the webhook a definitive indicator as to whether or not an action has ever been fired for this given Commit SHA before - or at least know whether or not this commit SHA has been previously committed/merged to this git repo.

This would be functionality similar to GitHub's commits[][distinct] payload field.

Workaround

using GitLab API-Created CI Jobs to manage state

Supposing that I have the ability to perform actions from the external system and that I can store GitLab Personal Access Tokens, I can use the GitLab Commit Status API to

1. Read to see if a given commit has ever received a particular action.
2. If no results are returned for a given job/build name, perform the task in the external system
3. Create and set the status for the given commit and build/job name.