rbenv: Отказано в доступе

Я следил за RailsCast Episode 339 Райана. Я установил rbenv и мог запустить ruby -v. Я вышел из сеанса, и когда я попытался вернуться (через su deployerиз root, я получил эту ошибку

/home/deployer/.rbenv/bin/rbenv: line 20: cd: /root: Permission denied

Вот rbenvфайл:

#!/usr/bin/env bash
set -e
[ -n "$RBENV_DEBUG" ] && set -x

resolve_link() {
  $(type -p greadlink readlink | head -1) "$1"
}

abs_dirname() {
  local cwd="$(pwd)"
  local path="$1"

  while [ -n "$path" ]; do
    cd "${path%/*}"
    local name="${path##*/}"
    path="$(resolve_link "$name" || true)"
  done

  pwd
  cd "$cwd"
}

if [ -z "${RBENV_ROOT}" ]; then
  RBENV_ROOT="${HOME}/.rbenv"
else
  RBENV_ROOT="${RBENV_ROOT%/}"
fi
export RBENV_ROOT

if [ -z "${RBENV_DIR}" ]; then
  RBENV_DIR="$(pwd)"
else
  cd "$RBENV_DIR" 2>/dev/null || {
    echo "rbenv: cannot change working directory to \`$RBENV_DIR'"
    exit 1
  } >&2
  RBENV_DIR="$(pwd)"
  cd "$OLDPWD"
fi
export RBENV_DIR


shopt -s nullglob

bin_path="$(abs_dirname "$0")"
for plugin_bin in "${RBENV_ROOT}/plugins/"*/bin; do
  bin_path="${bin_path}:${plugin_bin}"
done
export PATH="${bin_path}:${PATH}"

hook_path="${RBENV_HOOK_PATH}:${RBENV_ROOT}/rbenv.d:/usr/local/etc/rbenv.d:/etc/rbenv.d:/usr/lib/rbenv/hooks"
for plugin_hook in "${RBENV_ROOT}/plugins/"*/etc/rbenv.d; do
  hook_path="${hook_path}:${plugin_hook}"
done
export RBENV_HOOK_PATH="$hook_path"

shopt -u nullglob


command="$1"
case "$command" in
"" | "-h" | "--help" )
  echo -e "rbenv 0.3.0\n$(rbenv-help)" >&2
  ;;
* )
  command_path="$(command -v "rbenv-$command" || true)"
  if [ -z "$command_path" ]; then
    echo "rbenv: no such command \`$command'" >&2
    exit 1
  fi

  shift 1
  exec "$command_path" "$@"
  ;;
esac

Строка 20: cd "$cwd"

Любые идеи о том, почему я получаю эту ошибку, когда пытаюсь вернуться в сеанс?