It isnt weird this is simply a Pentium M stage. You dont need that adapter, you can also buy a Socket M board with 855GM.
Also if you have adapters to use Slot A in a Socket 462 board or Socket 423 in Socket 478 boards you really had the chance to use them, they were always allowed. I just doubt that those adapters exists.
Anyway, there are probably every week CT-479 adapters on ebay worldwide you can just grab one.