repository size limits (feature request)

On self-hosted gitlab instances with a lot of novice users (e.g., students) it would be nice to be able to limit the default repository sizes.

Novice users often push huge repositories including not only code, but data or even their whole home folder leading to a quite some admin intervention after the fact.

It would be great if admins could set a server-wide default size limit and override this per repository if necessary. This would allow us to drastically reduce accidental pushes, still allow our users to create repositories as they like and give us the flexibility to increase the size limit for certain repositories (after a discussion).

In case the user tries to push something which would make the repo size exceed the limit, the push should be rejected with an error message like "Push rejected because the repository would exceed the size limit of X MB. Reduce the repository's size or ask an admin to increase your limit." A force-push that reduces the repository size should always be allowed.