Mercurial project templates
With GitLab 13.7, the project templates become more prominent in the creation page, because users have to choose explicitely between "blank", "template" and "import", instead of being in the "blank" (used to be called "empty") creation form.
Perhaps it's time to introduce Mercurial project templates, or at the very minimum check if a user-defined template can be Mercurial, in other words: that templates can have vcs_type
fields.