Heroku PostGIS databases don't seem to be working

heroku_postgis_broken.sh

#!/bin/sh

set -e

APP=$1
APP_ARG=""
if [ "$APP" != "" ]; then
  APP_ARG=" -a $APP"
fi

DB_NAME=""
function finish {
	if [ "$DB_NAME" != "" ]; then
		CONFIRM_ARG=""
		if [ "$APP" != "" ]; then
			CONFIRM_ARG=" --confirm $APP"
		fi
		heroku addons:remove $DB_NAME $APP_ARG $CONFIRM_ARG
	fi
}
trap finish EXIT

set -x verbose

DB_URL=`heroku addons:add heroku-postgresql:ronin --version=9.1 $APP_ARG | grep Attached | sed -e s/.*HEROKU/HEROKU/`
if [ "$DB_URL" == "" ]; then
	echo "Error creating DB"
	exit 1
fi
DB_NAME=`echo $DB_URL | sed -e s/_URL//`
heroku pg:wait $APP_ARG
echo "Current PostGIS version (should error)..."
echo "select postgis_version();" | heroku pg:psql $DB_NAME $APP_ARG
echo "Enabling PostGIS"
echo "create extension postgis" | heroku pg:psql $DB_NAME $APP_ARG
echo "Now PostGIS version (should work)..."
echo "select postgis_version();" | heroku pg:psql $DB_NAME $APP_ARG