Prevent push to master branch

pre-push

# This blocks pushes into `master` locally. To enforce this for everyone with access
# to your repo, you should protect the branch with repository setting on Github
#
# 1. Save this file as .git/hooks/pre-push in your repo
# 2. Run `chmod +x .git/hooks/pre-push` to turn it on

branch_blocked=master
if grep -q "$branch_blocked"; then
    echo "Blocked by git pre-push. You should not push into '$branch_blocked'." >&2
    exit 1
fi