FWIW, this is what I wound up with - keeps the original branch name but ensures that it's based on the latest from the "dev" branch:

orig_branch=$(git branch --show-current) && git checkout dev && git pull && git branch -D "$orig_branch" && git checkout -b "$orig_branch"

Ah, excellent - appreciate the help! I'm already getting a ton of value out of this tool, thanks for sharing!