> How would you propose to fix broken bytecodes in a bugfix be fixed if you can't bump the magic number?

That would depend on the situation. I can imagine that if the bug is severe enough, the number could be bumped, after careful discussion, and with the change being advertised rather loudly.
The test case that's proposed can be changed if it's indeed the best thing to do, but it should at the very least be mentioned in release notes.


FWIW, I'm not convinced the bug here was severe enough. Practically no one is using the 3.5+ syntax in libraries: we checked to find that *zero* packages in Fedora are using the affected opcode. But that's moot now – wider discussion on that should have happened before the release.