<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=27587) </details> <!--IssueSummary end--> We have a lot of variables related to merge requests, like `CI_MERGE_REQUEST_PROJECT_URL`. We're lacking the basics: `CI_MERGE_REQUEST_URL` and `CI_COMMIT_URL`. Related commit where ~ 10 MR related environment variables were added: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24595/diffs CC @ayufan @jlenny @markglenfletcher