rails/rails — pull request #13376 by rosenfeld (2013-12-18 13:52:26+00:00)
Title: Use first path of migrations_paths to generate new migrations

This simplifies a lot to maintain separate gems to use AR migrations as a standalone project, like the active_record_migrations gem, since there would be no longer a need to use a new generator:

https://github.com/rosenfeld/active_record_migrations/blob/master/lib/active_record_migrations/generators/migration.rb