Review Apps initial seeding sometimes fail with a `ActiveRecord::RecordNotUnique: PG::UniqueViolation` error
Originally found that in https://gitlab.com/gitlab-org/gitlab-ce/issues/59113#note_151565191.
I found an interesting error at the beginning of the migrations job logs:
b28b22ac can be cherry-picked to output some debugging during the initial seeding.
Edited by Rémy Coutable