This repo is a mirror of the official Koha repo (where RM and RMaints push). It means it is automatically updated by gitlab every X minutes ("Mirrored from https://github.com/Koha-Community/Koha.git. Updated 15 minutes ago.")
If you fork this repo on gitlab you then can do the same with yours (mirror the one on gitlab), go to Settings, Repository, Pull from a remote repository, and fill it with https://gitlab.com/koha-community/Koha.git and tick "Only mirror protected branches". Stable branches (master, 16.05 to 18.05) are marked as protected and will be update automatically. It will ease branch comparaison via the gitlab UI.