Note that "you can only submit patches from your repo to the single repo that you forked from" is no longer true for GitLab starting with 10.1 (released October

Note that "you can only submit patches from your repo to the single repo that you forked from" is no longer true for GitLab starting with 10.1 (released October 22, see https://about.gitlab.com/2017/10/22/gitlab-10-1-released/#merge-requests-across-forks https://about.gitlab.com/2017/10/22/gitlab-10-1-released/#me...), and hasn't been true for GitHub for a while (perhaps forever).