Some permission user feedbacks get lost
In standard GitLab, push denies come with an explicit reason, which range from not very interesting "You are not allowed to upload code for this project" to actually useful "The repository is temporarily read-only".
The way permission checks work currently in Heptapod, except for the general access/visibility check, GitLab has no idea what the user is trying to do, and can only pass over a permission level to be used by Mercurial.
Hence these user feedbacks are lost. This isn't a big concern for the time being, and there's not so much we can do about it short time, but it's perhaps something we can improve within the hgitaly project.