Add automated information to merge request

My company uses the “number of additional commits” since a tag in our versioning.

i.e. $ git describe

The v1.0.4-14 number for example.

I’d like to modify the merge commit to include that information. I believe I found the code I need to modify in “embedded/service/gitlab-rails/app/models/merge_request.rb”. Are the tag and “number of additional commits” variables already available somewhere for me to use?