Perhaps I should limit myself to pointing out that:

"Everything was thrashed out in fine detail and agreed on before the change."

Is demonstrably false. About a day before the planned release of "BSD licensed" Shen 17, we were presented with this language for the master license:

The Shen license

Shen is under a 3 clause BSD license from 2015.

[ The standard language. ]

This license appears in the file BSD.

This license applies to all derived versions of Shen, including all versions derived from the sources provided whatever the method of compilation and the object code generated. This is the reason for clause 2 in the BSD. Such derived works should carry the above license on those source files generated – or with the files if they are binary. Any original code specifically written by the programmer which not derived from the sources supplied is and should be copyrighted to that programmer. This work may be placed under any license of choice except GPL because of the viral condition (see next paragraph)

There is no legal right to relicense or sublicense BSD code or any derived version to another license (e.g. GPL). The power to place a license on a work belongs to the copyright holder.

A person does not assume copyright over a work by making a small change to it. Only if the change is substantial to be deemed intellectually significant can such a claim be made and then only over the change itself. Hence if changing code, if you wish to retain copyright over your changes and they are intellectually significant, offset these changes under your copyright.

[ And Shen certification stuff. ]

There was no prior discussion that I can remember of adding language to the master license file, let alone "hashing out", and after multiple protests, the added language was retained with the 2nd paragraph appended to the 1st and the certification stuff moved to another file, with the following reframing. The initial two lines were changed to:

The Shen License = 3 Clause BSD

Shen is under a 3 clause BSD license from 2015. This license appears in the file BSD in the sources.

And the transition after the BSD license text was given this title:

Comment on BSD, GPL and Copyright