title: is it possible to reset the head of a branch while being on another branch i.e. without using git checkout?
body: <p>suppose I have two branches, A and B, and 3 commits C, D and E. C is the parent of both D and E and I'm on branch B which is on commit E. branch A is on commit C. Is it possible to, without checking out to branch A, reset branch A to commit D?
  The use case is that I'd like to git fetch and then update develop or master to origin/develop or master. Is this possible, ideally in a single command? I've seen git branch -f and I from my understanding, doing git branch -f A D might do what I want, but I'm not literate enough on the internals of git commands yet to be certain that that's what I want to do. So- to anyone who has more experience with git- does this achieve the desired effect? Could it have unintended side effects? And is there maybe a better way? One that might be safer? Also, would I need to address the commit I want to reset to as a hash or can I also use refs (so eg just do git branch -f master origin/master)?
  edit: forgot to mention what branch A points to</p>