Suppress push of certain branch to a certain remote.

pre-push.sh

#!/usr/bin/env bash

# pre-push hook to prevent push of certain branches to github.com
# copy this file to .git/hooks/pre-push
# and make it +x

REMOTE="$1"
URL="$2"
CURRENT_BRANCH="$(git rev-parse --abbrev-ref HEAD)"
FORBIDDEN_BRANCH="private" # change this to your private branch ...

if [[ "$CURRENT_BRANCH" == "$FORBIDDEN_BRANCH" ]]; then
    if [[ $URL =~ github.com ]]; then
        cat <<EOF
XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX

Not allowed to push $FORBIDDEN_BRANCH on to github.

XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX

Please contact your admin for further assistance.
EOF
        exit 1
    fi
fi