Releasing code in the open is an act of kindness. You help to scratch the same itch you had. But you don't know who will use this code. Mine ended in the heart of the cloud: containers. Mergo is a small library used to merge structs used by Docker, Kubernetes, and other big projects. And, because of one teeny tiny mistake, I broke a released version of Docker. This talk is the story of what happened and what lessons I learned.