OK, it seems that, as feared, automagic creation of debian/control is indeed fragile and needs special care. Although there are ways to make it work, the process will become more complicated than what I would like. It's much more straightforward to go for a scripted but manual packaging update and tests to check for inconsistencies between source tree ABIs and packaging. Stay tuned for a new MP.
OK, it seems that, as feared, automagic creation of debian/control is indeed fragile and needs special care. Although there are ways to make it work, the process will become more complicated than what I would like. It's much more straightforward to go for a scripted but manual packaging update and tests to check for inconsistencies between source tree ABIs and packaging. Stay tuned for a new MP.