Allow choosing fork as source/destination for merge requests
Currently merge requests seem to be rather limited in which directions merges are allowed to be submitted;
The master project is only allowed to submit merges from itself to itself, while forks can only submit from themselves towards themselves or their master.
Master -> Master Fork#1 -> Fork#1 Fork#1 -> Master
So merges like the following are all impossible to create;
Fork#1 <- Master Master <- Fork#1 Fork#1 -> Fork#2 Fork#1 <- Fork#2
Ideally, you'd be able to submit merges in both directions, for instance adding MR's for merging the master project into your fork or possibly any other forks you have the rights for.
Additionally, merge requests should be able to be created both from the context of the master project as well as your fork. Seems a bit strange to force you to submit a merge towards master as a merge request inside your fork after all, more logical would be to go to the master project and open a merge request on there.
Links / references
GitHub currently allows you to submit merges from any ref you can access to any ref you have permission to, which seems a much more useful way to go about it.