If you prefer to always work in a detached head state, this will allow you to quickly do a PR and return to master w/o creating branches

groll.sh

#!/bin/bash

git checkout -b $1
git push origin $1
hub pull-request
read -p "back to master? <y/N> " prompt
if [[ $prompt == "y" || $prompt == "Y" || $prompt == "yes" || $prompt == "Yes" ]]
then
  git fetch
  git checkout origin/master
else
  git checkout HEAD^1
fi