You could follow a solution similar to "How do I force “git pull” to overwrite local files?":
git fetch --all
git reset --hard origin/abranch
git checkout $branch
That would involve only one fetch.
With Git 2.23+, git checkout is replaced here with git switch (presented here) (still experimental).
git switch -f $branch
(with -f being an alias for --discard-changes, as noted in Jan's answer)
Proceed even if the index or the working tree differs from HEAD.
Both the index and working tree are restored to match the switching target.