Rebase action not available when CI failed
Description
We use "Merge commit with semi-linear history" that requires us to rebase many MRs. Sometimes issues happen with the CI system, either a broken CI or something magical with a build. In the mean time other MRs might have been merged.
When a MR has a failed CI build, it can't be rebased until there's a valid CI build. But some scenarios would actually fix a CI bug in a different MR so that would then require a local rebase.
Proposal
Allow rebases when there is a broken CI build.