git fetch: how to ignore new branches
You can edit .git/config and change
fetch = +refs/heads/*:refs/remotes/origin/*
to, for example,
fetch = +refs/heads/master:refs/remotes/origin/master
Also you can do git fetch origin +refs/heads/master:refs/remotes/origin/master each time instead of just git fetch
You can create fetching script (like "gfm") to avoid inputting that string each time. This way you can use "gfm" to fetch just master and "git fetch" to fetch everything.