SAN FRANCISCO (KCBS) &mdash KCBS has learned that Saint Mary’s Cathedral, the principal church of the Archdiocese of San Francisco, has installed a watering system to keep the homeless from sleeping in the cathedral’s doorways. The cathedral, at Geary and Gough, is the home church of the Archbishop. There are four tall side doors, with sheltered alcoves, that attract homeless people at night.“They actually have signs in there that say, ‘No Trespassing,’” said a homeless man named Robert. But there are no signs warning the homeless about what happens in these doorways, at various times, all through the night. Water pours from a hole in the ceiling, about 30 feet above, drenching the alcove and anyone in it. Not quite a Godly approach.