I think i didn't explain well my point.

ActsAsTaggableOn::Tag extends ActsAsTaggableOn::Utils. So i think it better to do  ```if ActsAsTaggableOn::Utils.supports_concurrency?``` instead of ```if ActsAsTaggableOn::Tag.supports_concurrency?``` since ActsAsTaggableOn::Tag has nothing to do with supportins concurrency

This is just a suggestion .