Why was Willie Brown -- that's him on the left -- involved in sponsoring an Assembly bill the city's Board of Supervisors is madly hoping to derail?It probably wasn't really Mark Twain who said "Whiskey is for drinking; water is for fighting over." But until the day 80-proof distilled spirits begin rolling in via the tunnels from Hetch Hetchy, it seems the city of San Francisco will have a hard time winning any water wars when one Willie L. Brown, Jr. is on the other side. This story is a