Outdated error message
This error upon
remote: GitLab update error: 'You can only use an existing protected branch ref as the basis of a new protected branch.'. Because of this, some changes won't be visible in the web interface remote: You can only use an existing protected branch ref as the basis of a new protected branch. abort: push failed on remote
Nowadays, we're firing the pre-receive ourselves, and that is before the Mercurial transaction commit, outlined by the
abort: push failed on remote, so "Some changes won't be visible" is outdated, it would make sense only for the post-receive send, which happens, as expected, after Mercurial transaction is complete.