GitLab

Before this commit some migration specs failed with

    4) Gitlab::BackgroundMigration::DeleteDiffFiles#perform when diff
       files can be deleted rollsback if something goes wrong
       Failure/Error: return false if internal?

       NameError:
         undefined local variable or method `bot_type' for
           #<User id: @namespace1117>
         Did you mean?  bot_type=
                        bot_type?
       # ./ee/app/models/ee/user.rb:281:in `bot?'
       # ./ee/app/models/ee/user.rb:277:in `internal?'
       # ./app/models/user.rb:1452:in `password_required?'
       # ./ee/app/models/ee/user.rb:290:in `password_required?'

https://gitlab.com/gitlab-org/gitlab-ee/-/jobs/185393284

It's because we migrate down before each migration spec which actually
introduces `bot_type`.