git-fork

#!/bin/bash

if [ "$#" -gt 1 -o -z "$1" ]; then
  echo "Usage: $0 new-branch"
  exit 1
fi

current_branch=$(git rev-parse --abbrev-ref HEAD)
new_branch=$1

git checkout -b "$new_branch"

git config --null --get-regexp "^branch\.${current_branch}\..*" | (
  while read -r conf_var; do
    new_var="branch.$new_branch.${conf_var#branch.$current_branch.}"
    read -r -d '' value
    git config --add "$new_var" "$value"
  done
)