### Description I have several scripts working with github repos where I can update by asking for the latest SHA for an arbitrary branch. In one case the SHA is used as a cache invalidation for the script. My goal is to achieve the same on GitLab hosted projects. ### Proposal Add support for `Accept` header on API endpoints, in our case: `GET /projects/:id/repository/commits/:ref` should be able to accept something like `application/vnd.gitlab.VERSION.sha`, where `VERSION` is the API version. This endpoint should simply return the SHA of the latest commit in this REF, whether branch or tag, in case of an actual SHA, the returned SHA will simply be identicatl, but that is the user's issue... ### Links / references This is Github's content-type: https://developer.github.com/v3/media/#sha At the time of writing this issue, I ran this call: ```bash $ curl 'https://api.github.com/repos/gitlabhq/gitlabhq/commits/master' -H 'Accept: application/vnd.github.v3.sha' e1de8a77d5d9749eaa596bfa15e6d11f1828db95 ```