@beaufils Yeah, it's a huge part of the problem. Distributing identities and authorization is hard, to say the least :/
Anyway, without being able to create a pull request from one instance to another, self-hosted gitlab (or whatever) instances are no workable replacement for contralized platforms like github, where basically everyone already has an account and can easily contribute to other projects hosted there
BTW, gitlab has an open issue for this: https://gitlab.com/gitlab-org/gitlab-ce/issues/4013
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