Well, now what? I bet nothing will happen -- the only way these licensing violations pique the lawyers' interest is when they are perpetrated by a high profile company with some money in the bank.
Well, if they don't fulfill the license conditions and keep distributing theirs they're violating copyright. Would a DMCA takedown from one of the authors be valid?
Bonus question, since mozilla has made themselves the single trust root of all addons, could one request that they refuse code-signing (something something contributory infringement) of the extension as part of the DMCA process?
Well there's this: https://web.archive.org/web/20160726212936/https://github.co...
That's probably a much worse outcome for Buu than a DMCA notice or otherwise.
The only people who do are those who contributed to the project under the understanding that their contributions were covered under the main license.
Of course a major issue is that such projects often accept submissions from other people, which creates major headaches if a change a license is later sought.
Edit: an issue that it is very often not discussed or clear on what basis people can make contributions, and I think that the default position must be that they retain the copyright over their contributions (but is it implied what licensing they are agreeing with?)
Edit 2: I understand that he is not the the sole author, but that does not make anything I wrote incorrect or irrelevant. A lot of drama for some reason...
Absolutely, but he isn't the sole author: https://github.com/ovity/octotree/graphs/contributors
I'd imagine that he knows this, which is why he's pretending that the proprietary Octotree is a "complete rewrite".
From your link the contributions do not look huge so it seems that removing them is quite doable.
Example: https://github.com/christianbundy/octotree/issues/1#issuecom...
If the maintainer wants to remove the AGPL without copyright infringement, I think they'd need to delete most/all of pjax.js and have someone else write a clean-room implementation that isn't built on contributions from someone else.
The reason people do cleanroom is to eliminate risk of liability, it's simple, and it's foolproof. You can't mess it up. It also eliminates other potential issues (like tortious interference with someone who signed an NDA).
Legally, it's overkill. It's like using a thermonuclear bomb to swat a fly.
If you're going up against Microsoft, overkill absolutely makes sense; you might be legally right, but it will take millions of dollars in legal fees to show that. Programmers are cheaper than lawyers.
In the general case, though, you can just rewrite the old code and be done with it. Yourself. Looking at the old code too, so long as you don't borrow it. You want to be a little bit careful since it's not just the literal words (you can break copyright on a novel if you rewrite the same plot in your own words; same thing with code), but "a little careful" suffices.
It's a bit harder to transform a piece of code into something non-infringing, rewriting section-by-section, but most lawyers say that's not impossible either.
(Of course, clearly, none of that happened in this case)
[1] https://github.com/ovity/octotree/graphs/contributors
[2] Not to diminish the effort of submitting even a one-line PR, just in the sense of "de minimis" in terms of copyrightability.