Navigation to Labels impossible without internal issue tracker
"Labels" are used for both Merge Requests and Issues but the navigation left-bar only lists them under "Issues". If one disables the internal issue tracker there is no way to navigate to the Labels page anymore via the UI. One has to manually type the URL. This seems to have been discussed previously on gitlab-ce#2525 (closed) but the reporter seems to have ignored that labels are also used for merge requests.
Steps to reproduce
Disable Issues under "Settings - General - Permissions - Issues" The left bar will no longer contain the "Issues" navigation.
It may be better to have the Issue navigation linked under the "Repository" navigation as they apply to both merge requests and issues.