However the key part is "We agree to ALSO license the Contribution" they DO NOT say it will ONLY be licensed under that licence. So they can create any number of forks under different licences and still conform to their agreement because your contribution is licenced under the GPL in version 1. They have every right to licence Version 2 under a closed licence only.
If you are interested the highest profile case I can think of this type of thing happening is with Open Office (originally under GPL). Sun used to have a similair agreement for Open Office contributions. Sun changed the licence so that it could licence the code to IBM under a closed source arrangement and when Oracle took over this is how they were able to relicence it to an apache licence and donate it to the apache project. Anyway thats why LibreOffice is GPL and OpenOffice is now Apache.