SHELL

git move branch to previous commit

git checkout 1258f0d0aae    #detach from master
git branch -f master HEAD   #exactly as above

#optionally reattach to master
git checkout master

move branch to a commit

git checkout master
git reset --hard 1258f0d0aae

git move latest commit to new branch

git checkout existingbranch
git branch newBranch
git reset --hard HEAD~2 # go back 2 commits on existingBranch