Git command to checkout any branch and overwrite local changes

Question

Is there a Git command (or a short sequence of commands) that will safely and surely do the following?

• Get rid of any local changes.
• Fetch the given branch from origin if necessary
• Checkout the given branch?

Currently I'm stuck with:

git fetch -p
git stash
git stash drop
git checkout $branch
git pull

but it's bothering me because I'm asked for password two times (by fetch and pull). Generally I would be happy with any solution as long as the password is needed only once.

A couple of notes:

• It's a part of homebrewed deployment script for an application (the code is hosted on GitHub).
• There should be no difference if the branch was already fetched from origin or not (i.e. the first deployment of a new branch shouldn't ideally require any additional steps).
• The script is located on a remote machine that can be accessed by several people, hence no credentials are stored and user/password must be entered (but only once if possible).
• I don't care about any local changes; I always want a pristine copy of the given branch (the further part of deployment script produces local changes).
• I can't clone or export a fresh repository each time; it takes too much time.

Answer 1

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.