https://www.macrumors.com/2005/05/11/apple-seeds-mac-os-x-10-4-1-8b13/
Apple Seeds Mac OS X 10.4.1 (8B13) - MacRumors
Apple has apparently seeded Mac OS X 10.4.1 Build 8B13 to developers. The upcoming Mac OS X update is expected to arrive in mid-may.
mac os xapple seedsmacrumors