[plt-scheme] different PlaneT repositories

Hello!

What is the reason for introducing two different PlaneT repositories for PLT
Scheme v20x and v299.x-30x ?

How can I obtain the package from the PlaneT repository v20x with PLT v299 ?
Currently, I get the error message:

> (require (planet "test-connection.ss" ("planet" "test-connection.plt" 1
1)))
planet: Could not find matching package in: (planet "test-connection.ss"
("planet" "test-connection.plt" 1 1))

Regards,
Dmitry