updates were rejected because a pushed branch tip is behind its remote heroku code example
Example 1: git updates were rejected because the tip of your current branch is behind
git push -f origin master
Example 2: Updates were rejected because a pushed branch tip is behind its remote
// if this don't work
git pull origin FixForBug
git push origin FixForBug
// then, do this:
git push -f origin FixForBug