The present question is a special case of Can one take BSD licensed code and distribute it under GPL?.
Looking recently at OpenBSD's LibreSSL, I've noticed that SSLeay that it traces its roots to (through the OpenSSL lineage), has had the following addendum to what otherwise looks like the standard 4-clause BSD licence:
* * The licence and distribution terms for any publically available version or * derivative of this code cannot be changed. i.e. this code cannot simply be * copied and put under another distribution licence * [including the GNU Public Licence.] */
Is it or is it not a NOOP, considering the possible answers from the prior question? (Alas, the prior question has completely conflicting answers at this point!)
Why is GNU Public Licence specifically mentioned; isn't GPL already incompatible with the 4-clause BSD licence that precedes the above comment, due to the advertisement clause?