DB migrate: column "closed_at_for_type_change" does not exist

Ever since 10.4 my DB migration has been failing with

PG::UndefinedColumn: ERROR:  column "closed_at_for_type_change" does not exist
    : ALTER TABLE "issues" RENAME COLUMN "closed_at_for_type_change" TO "closed_at"
    /opt/gitlab/embedded/service/gitlab-rails/lib/gitlab/database/migration_helpers.rb:442:in `block in cleanup_concurrent_column_type_change'
    /opt/gitlab/embedded/service/gitlab-rails/lib/gitlab/database/migration_helpers.rb:438:in `cleanup_concurrent_column_type_change'
    /opt/gitlab/embedded/service/gitlab-rails/db/post_migrate/20171106180641_cleanup_add_timezone_to_issues_closed_at.rb:12:in `up'

I've searched for quite a while and there are one or two references to this (mainly from EE) but I haven't found a solution yet. I tried upgrading one release at a time from 10.3.3 but I still have this failure. I also saw in the changelog a reference to tidying this up. I haven't done anything non-standard - just ordinary, one node Debian package upgrades.

many thanks for any pointers, Dave