Can a Mercurial fork change its license to AGPL?

[Mads Kiilerich]

On 02/28/2015 02:21 AM, Matt Mackall wrote:
> On Sat, 2015-02-28 at 09:26 +0900, Kaz Nishimura wrote:
>> I found a fork of Mercurial named Quicksilver <
>> http://hg.quicksilver-vcs.org/quicksilver> is being licenced under the GNU
>> AGPL.  Is it permitted to change a fork to the AGPL by the Mercurial
>> copyright holder(s)?
> Nope. Generally speaking you can't remove restrictions from a license..
> or else copyright would be meaningless. The GPL says "we give you the
> privilege to copy.. but you lose that if you try to restrict your
> changes".

I'm not so sure it is that clear. From some point of view, the AGPL is 
more Free than GPL; it will be argued that AGPL adds a freedom, not a 
restriction. GPLv3 explicitly permits everybody to combine GPLv3 work 
with AGPL work and ship the combined work as AGPL - just like GPL code 
can embed BSD/MIT licensed code and ship the combined work under GPL.

http://hg.quicksilver-vcs.org/quicksilver/rev/7eb0dd0734af is thus not 
necessarily a violation, even though it could/should make it more clear 
that the whole work is a combination of GPL and AGPL work and perhaps 
point out where the GPL part of the combination can be found (which 
could be a link to a mirror of the upstream repo).

http://hg.quicksilver-vcs.org/quicksilver/rev/ab8914b3657e is more 
problematic as it obfuscates the original license (even though they take 
care to preserve attribution and copyright).

/Mads
Not A Lawyer