Would it be possible for the plan 9 foundation to assemble an iso file with all parts of plan 9 and contributed code as downloadable from the website where in the root folder the new MIT license could be placed so that developers exactly know what is really part of this new license ?
As an example
http://9p.io/sources/contrib/steve/ contains the cfront package with sources. As far as I know cfront is licensed differently but the header of the site states that all those contributed sources are licensed with the MIT license.
The only people who exactly know what was relicensed are the members of the plan 9 foundation. A statement at the header of a webpage isn't really assuring for developers who intend to take the code and base their future development on that.
There are also packages in those folders which where GPL licensed in the past and as far as I know it's nealy impossible to relicense packages from GPL back to more permissive licenses when more than a few people worked on those projects.
The situation seems clear for the four released plan9 CDs but regarding the n/sources/contrib folder it would be nice if the foundation could make things clearer.