Add SSPL to distributable_lib.tcl to make mongodb (more) distributable

[ryandesign (Ryan Carsten Schmidt)]

mongodb switched their license from the AGPL to the SSPL, a new non-OSI-approved license they created which, like the AGPL, is based on GPL-3 but with additions for to licensing requirements for server side infrastructure related to a mongodb deployment.

Here is a ​FAQ about the SSPL. In particular it says:

The only changes are additional terms that make explicit the conditions for offering a publicly available MongoDB as a service.

and:

The only substantive modification is section 13, which makes clear the condition to offering MongoDB as a service.

I think the thing to do is to add the SSPL to distributable_lib.tcl​ but I'm not clear exactly what needs to be changed in good_licenses and license_conflicts to accomplish that. I assume that everywhere AGPL is currently mentioned, a similar mention should be made of SSPL, but I don't know whether or how the distinction between "AGPL" and "AGPL-1" applies to SSPL. Or if something else should be done, let me know.

[jmroot (Joshua Root)]

Updating good_licenses is easy, it's just a list of all known licenses that are distributable on their own. The conflicts are the tricky part. If SSPL is adding additional terms to GPL-3, then presumably it conflicts with all other extant GPL versions and variants (AGPL, CeCILL) as well as all the things that GPL-3 conflicts with. But someone need to actually read the license and compare the differences, and consider what other commonly used license terms might conflict with it.

I don't know whether or how the distinction between "AGPL" and "AGPL-1" applies to SSPL.

In the conflicts, a license name with no trailing version means all versions of that license. So the distinction between "AGPL" and "AGPL-1" is like the distinction between "GPL", "GPL-1", "GPL-2", and "GPL-3". The current version of the SSPL is 1, but since there are no other versions currently, it only needs unversioned conflict entries.

[ryandesign (Ryan Carsten Schmidt)]

Has duplicate #69451.