Git clone reveals private repo's presence

Corresponding issue on dev: https://dev.gitlab.org/gitlab/gitlabhq/issues/2813

Summary

Steps to reproduce

Try to clone a private repo that exists and try to clone a repo that doesn't exist

What is the current bug behavior?

It can be used to determine wether a private repo exists or not

What is the expected correct behavior?

It should behave like github, like this:

Output of checks

Happens on gitlab.com