I like the fact that autopkgtests are detecting this issue. The older libiso9660 should work with the newer libcdio, because libcdio did not break its ABI. I was thinking of investigating this further (e.g. with a minimal reproducer, if I can make one) and even involve upstream if something is indeed broken. The reason why I want to do this is that the problem does not seem to be related to libdevice-cdio-perl, but a problem with libcdio itself.
This would most likely delay the transition after the trixie release.
