Squash and merge basic implementation

squash_n_merge.sh

fancy_branch_descr() {
  local fancy=${1//[-_]/ }
  echo ${fancy^}
}

create_commit_message() {
  local base=$1 branch=$2
  fancy_branch_descr $branch
  git log --pretty=format:"%n* %s" ${base}..${branch}
}

squash_n_merge() {
  local base=$1 branch=$2 msg_file=$(mktemp) head

  create_commit_message $base $branch > $msg_file

  # Squash commits
  git checkout --detach $branch
  git reset --soft $base
  git commit -m "$(cat $msg_file)"
  head=$(git rev-parse HEAD)
  rm $msg_file

  # Merge
  git checkout $base
  git merge $head
}

# If `branch` was based on `squashed` and `squashed` was squashed and merged into `base`,
# this allows you to rebase `branch` on `base` without the `squashed` commits
rerebase() {
  local base=$1 squashed=$2 branch=$3
  git rebase --onto $base $squashed $branch
}