Sync a GitHub fork

sync.sh

git remote -v
# List the current remotes
# origin  https://github.com/user/repo.git (fetch)
# origin  https://github.com/user/repo.git (push)

git remote add upstream https://github.com/otheruser/repo.git
# Set a new remote

git remote -v
# Verify new remote
# origin    https://github.com/user/repo.git (fetch)
# origin    https://github.com/user/repo.git (push)
# upstream  https://github.com/otheruser/repo.git (fetch)
# upstream  https://github.com/otheruser/repo.git (push)

git fetch upstream
# Grab the upstream remote's branches
# remote: Counting objects: 75, done.
# remote: Compressing objects: 100% (53/53), done.
# remote: Total 62 (delta 27), reused 44 (delta 9)
# Unpacking objects: 100% (62/62), done.
# From https://github.com/otheruser/repo
#  * [new branch]      master     -> upstream/master
# We now have the upstream's master branch stored in a local branch, upstream/master

git branch -va
# List all local and remote-tracking branches
# * master                  a422352 My local commit
#   remotes/origin/HEAD     -> origin/master
#   remotes/origin/master   a422352 My local commit
#   remotes/upstream/master 5fdff0f Some upstream commit

git checkout master
# Check out our local master branch
# Switched to branch 'master'

git merge upstream/master
# Merge upstream's master into our own
# Updating a422352..5fdff0f
# Fast-forward
#  README                    |    9 -------
#  README.md                 |    7 ++++++
#  2 files changed, 7 insertions(+), 9 deletions(-)
#  delete mode 100644 README
#  create mode 100644 README.md