Just for anyone else following along..you're right. Here it is.
git fetch -p && git branch -vv | awk '/: gone]/{print $1}' | xargs git branch -d git fetch -p && git branch -vv | awk '/: gone]/{print $1}' | xargs git branch -d
[0] https://stackoverflow.com/questions/20106712/what-are-the-di...