Hard reference to APIv3 in Mattermost configuration
We make a specific reference to the GitLab Auth endpoint when configuring MM: https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-config-template/gitlab.rb.template#L1092
As recent as 9.4.1, that URL was set for APIv3. This means that anyone who has customized this, which you have to do in a few scenarios, will be locked to APIv3 unless they update their gitlab.rb
manually.
This seems like a painful challenge for the removal of APIv3.