NzbDrone v1533 - Added SPK compatibility for built-in NzbDrone updates!

SPK now versioned by date for multi-branch and built-in NzbDrone updater compatibility - SPK upgrade now retains current NzbDrone binary (avoids potential binary downgrade) when necessary
Same here: reaching the preuninst point means package is already stopped. Page 36 of the developers guide, this time ;)