Automatically prepend git commit message with a branch name

prepare-commit-msg.sh

#!/bin/sh
#
# Hook script to prepend the commit log message with a branch name
# Prepend the name of the branch only if:
# - branch name starts with one of the options in $BRANCH_STARTSWITH
# - branch name has not been manually prepended in the commit message

BRANCH_STARTSWITH=(dev- WIP XYZ-)
BRANCH_NAME=$(git symbolic-ref --short HEAD)
COMMIT_MESSAGE=$(cat $1)
PREPEND=0

for PREFIX in "${BRANCH_STARTSWITH[@]}"
do
    if [[ $BRANCH_NAME == $PREFIX* ]]; then
        PREPEND=1
        break
    fi
done
echo $PREPEND
if [ "$PREPEND" -eq 1 ] && [ -n "$BRANCH_NAME" ] && ! [[ $COMMIT_MESSAGE == $BRANCH_NAME* ]]; then
    sed -i.bak -e "1s/^/$BRANCH_NAME /" $1
fi