Sync-fork.txt

# Add the remote, call it "upstream":

git remote add upstream https://github.com/whoever/whatever.git

# Fetch all the branches of that remote into remote-tracking branches,
# such as upstream/master:

git fetch upstream

# Make sure that you're on your master branch:

git checkout master

# Rewrite your master branch so that any commits of yours that
# aren't already in upstream/master are replayed on top of that
# other branch:

git rebase upstream/master

If you don't want to rewrite the history of your master branch, (for example because other people may have cloned it) then you should replace the last command with git merge upstream/master. However, for making further pull requests that are as clean as possible, it's probably better to rebase.

Source: https://stackoverflow.com/questions/7244321/how-do-i-update-a-github-forked-repository

----
git push --all
git push --tags
git push -f origin refs/remotes/upstream/*:refs/heads/*

Source: https://stackoverflow.com/questions/15779740/how-to-update-my-fork-to-have-the-same-branches-and-tags-as-the-original-reposit