Allow internal fetches to see all hidden references
When re-homing a repository, it was noted at https://gitlab.com/gitlab-org/gitlab/issues/35864 that not all objects were copied across, most notably keep-around
refs (but there could be others).
Stan suggested we:
Allow internal fetches to see all hidden references (e.g.
refs/keep-around/X
,refs/merge-requests/Y
, etc.) if requested. This may involve changes in gitlab-shell (e.g. gitlab-shell!150 (diffs)), Gitaly, and the internal API.