[sangnoir]

When people say BSD-style licenses are "more permissive" than GPL - this is what they mean. You truly can do whatever you want, as long as you observe the license requirements (i.e. retain the BSD license notice). One can close-source a fork (but keep the notice), or add an additional compatible license like the GPL or AGPL (but keep the BSD notice), or add a license that bars use by cat-lovers (but keep the BSD notice).

> I'm not so sure, if the go authors are happy about that.

Then they should probably switch to a different license - one that more closely mirrors their intent. The cat's out of the bag for all released versions though.