Mercurial rollbacked, yet some of the changes are visible in the UI
This happens for me while importing (#60 (closed)) pathological repos.
This is a drawback of our current three steps push to the inner auxiliary Git repository. If the first step (topics) passes then the auxiliary Git repository will get its push and notify GitLab. If the second one fails, Mercurial will rollback, but Git(Lab)'s won't.
We should factorize these three pushes, do all the mapping logic earlier, and fail early before actually pushing to the inner Git repository. This is probably to be done before #73 (closed), for which there'll be a clearer path once this is taken care of.