Which, as someone pointed out in a separate comment thread here, Homebrew is already doing. I'm not sure what else you want from them, they seem to be following best practices here.
The notification when it first came out wasn’t really noticeable for a tool that frequently has a lot of output an average user running `brew upgrade` would be used to ignoring. Prompting would have been the better choice. I didn’t notice until the change hit HN and created a bit of a shit storm.
PS: Despite my feelings of disagreement on how brew handled this, I still appreciate your work.
