(Xmas shopping got in the way) but I have at last tried installing migratepassword by editing app.yml and rebuilding and … it worked !
But the bundle exec rake plugin:install repo=http://github.com/[Communiteq](https://www.communiteq.com) (formerly DiscourseHosting)/discourse-migratepassword option does not work on my vanilla install, maybe this needs checking/removing in the GitHub - communiteq/discourse-migratepassword: Support migrated password hashes · GitHub README.md