I needed to update my test environment, so I ran bundle exec rake db:migrate RAILS_ENV=test
And I got the following error:
The problem is with the language creation:
There should be a sortable_name specified, and it should be "English".
Testing
Since this is a fallback, the best way to test this is probably for a dev to pull the changes, comment out the rest of the file to ensure this part is used, and then run bundle exec rake db:migrate RAILS_ENV=test
Resolved with an update to the instructions for updating local installs to utf8mb4 – thanks, red!