Exclude rails 4.2 + MRI 2.6+
Exclude rails 4.2 + MRI 2.6+

c.f.

* https://github.com/cucumber/cucumber-rails/pull/400
* https://github.com/rails/webpacker/pull/1825
mitaku/komachi_heartbeat,mitaku/komachi_heartbeat,mitaku/komachi_heartbeat