Romain Francoise wrote:
But now that I think more about the whole thing, there is another problem: if /usr/bin/emacs-snapshot becomes an alternative, it'll be set up from the first subflavor's postinst, and there's a good chance that it would be too late if an Elisp package's postinst runs before the subflavor's (it would try to run `emacs-snapshot' and that wouldn't exist yet).
On closer inspection, I am sure that this cannot happen, because a package's postinst must call (by Debian's Emacs policy) /usr/lib/emacsen-common/emacs-package-install <package-name>. And emacs-package-install will only take actions for flavors which are already registered in /var/lib/emacsen-common/installed-flavors, which registration will only be done when the subflavors' postinst runs 'emacs-install'. Quod erat demonstrandum.