Build the merge result for a merge request, not the merge source
Description
I thought you're already tracking this but it seems not the case. Currently GitLab only sends the source branch to the CI build for a merge request. This is all nice, but after a merge, new bugs may be introduced. So what we actually need to check is the merge result. AFAIK BitBucker can do this for some time (I think this is the source), and now I've seen that TFS also does it. Will GitLab also support this one true useful way to CI-build merge requests?