AGPL can be combined with GPL and vice versa. GPL does not require open-sourcing if it stays on your computer or the computer of your company and its employees. This makes AGPL a much weaker copyleft when on a server.
I don't understand the distinction you're drawing. It sounds like you're saying that "cannot be combined with code under a different license" is meaningfully different from "can be combined with code under a different license, so long as you immediately relicense that code so it's not under a different license anymore". What am I missing?
Because you're misreading it. It doesn't say you have to relicense the code. It just says (A)GPL terms have to apply to both parts of the code. That's not relicensing. You don't need anyone's permission for weakly-licensed code to do that. Weakly-licensed code already allows it, that's why it's a weak license.
Weakly-licensed code also allows to be covered by a proprietary license. Nobody needs to relicense weakly-licensed code to lock it up in any way and apply further restrictions to it, whether they be "good" restrictions like the (A)GPL, where you forbid further restrictions, or "bad" restrictions like a EULA, where you forbid people to look at your modifications or to do further modifications.
Without a copyright transfer agreement in place, only the original author may relicense the code. The permissively licensed parts of the code will stay permissively licensed, but nevertheless may be distributed in combination with copyleft or proprietary code.
c) You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy. This License will therefore apply, along with any applicable section 7 additional terms, to the whole of the work, and all its parts, regardless of how they are packaged. This License gives no permission to license the work in any other way, but it does not invalidate such permission if you have separately received it.
This only says that the product of such a combination must be licensed as AGPL. The MIT/BSD licenses (with or without the attribution clause) specifically allow being included in larger works under any license, even proprietary, so what are you arguing exactly?
I have an MIT-licensed project called A, currently at version A1. You have an AGPL-licensed project called B. I take some code from B and incorporate it into version A2 of project A. I want to distribute A2 to A's community.
I don't have to relicense A1 to do this, but I do have to distribute A2, and all subsequent versions of A, under the AGPL, effectively "changing the license" of my project.
I realize this usage is informal - licenses cover code, not projects - but jrv's point upthread was that projects do not want to change their working license, which led me to read jordigh's response as somehow asserting that the AGPL was not viral. It's a non sequitur otherwise.