tldr;
git fetch --all (or git remote update)git pull --all
Important for projects with multiple remotes:git checkout -t origin/branch-name
This last piece will prevent a detached-head situation when adding branches that currently only exist on remote.
https://stackoverflow.com/questions/10312521/how-to-fetch-all-git-branches
https://stackoverflow.com/questions/1783405/how-do-i-check-out-a-remote-git-branch
💩