We are working on integrating GitLab (enterprise edition) in our tooling, but one thing that is still on our wishlist is to create a merge request in GitLab via a command li
If you push your branch before this command (git push -o merge_request.create) it will not work. Git will response with Everything up-to-date and merge request will not be created (gitlab 12.3).
When I tried to remove my branch from a server (do not remove your local branch!!!) then it worked for me in this form.
git push --set-upstream origin your-branch-name -o merge_request.create