Moving ghc-head PRs to Gitlab

[Kleidukos]

@bgamari has suggested that it would be more convenient for everyone if we had the PRs destined to ghc-head opened and managed in the GitLab mirror. I am personally in favour of this, but I would like your opinion @hsyl20 @alexbiehl @sjakobi.

[bgamari]

To fill in a bit more context: Currently there are really two distinct types of development that Haddock sees:

1. Functional changes to the documentation generator
2. Changes simply updating haddock-api to accommodate changes in GHC

Under the proposed scheme, changes of type (2) would be managed on GitLab on the ghc-head branch whereas all other changes would remain here on GitHub. Periodically (e.g. ideally every month or two but at very least before every major GHC release) we would then merge the two branches.

[hsyl20]

Yes! It makes no sense to do the PR here where CI and reviewers can't check if it builds. In addition we could perhaps teach Marge to merge wip/ branches to ghc-head => no more serialization of GHC's MRs.

[bgamari]

Yes! It makes no sense to do the PR here where CI and reviewers can't check if it builds.

Agreed.

In addition we could perhaps teach Marge to merge wip/ branches to ghc-head => no more serialization of GHC's MRs.

Yes, this would make life so much easier.

[simmsb]

Hey, I have CI functioning on the ghc-head branch here https://github.com/simmsb/haddock/actions/runs/698326272
The required changes to haskell/actions are in this PR that I'm waiting on: haskell/actions#42

[Kleidukos]

@simmsb sorry for the delay, I hope you'll be able to resume your work on the CI