The original codebase was MIT, and we relicensed when a commercial product and a community project were formed.
Here is where we announced it:
The discussion was among the most involved contributors, and then we asked everyone to sign them being OK with it:
@nicksellen @hedgedoc This becomes increasingly difficult with more contributors, of course, but that is - I think - a good thing. A license is a contract for everyone involved that sets the terms what will be done with their contributions. I think such a change _should_ be somewhat difficult.
This is also the reason why I do not like CLAs where developers (and other contributors!) give up their own rights to their code. I think this is putting too much power in to too few hands.
I think contributor agreement is unlikely for the forked project, this has 185 contributors (from "git shortlog -s -n") and we are a fork which itself was a fork from a starter project (including all those contributors). These 185 contributors are not even part of our project!
Given with MIT you can incorporate the code in a proprietary product, I wonder how to do that (distinguishing which code is MIT and which is proprietary), and whether that is an option...