Currently it links to a gateway page for GPLv2 and GPLv3 but isn't specific about which one the file is.
It has been like that in phpBB before GPL3.0 was created but now that url was turned into a sort of 'gateway'. MPV and (probably) soon to be Titania to have already have made this change.
I suggest (and if the team say this should be done, I can complete a patch for it) that the link it changed to the GPLv2 page on that gateway page.
|License in migrations header not linking to version 2 of GNU GPL||Unverified Fix|