[feladat @ 88]
Bugfix. When viewing the details of a slave zone, an error was shown
if the ip addresses of it's master nameserver was set (instead of
showing the error if there was none set. Reported: Maarten te Paske.
printf(_('You are about to delete a slave zone of which the master nameserver, %s, is a supermaster. Deleting the zone now, will result in temporary removal only. Whenever the supermaster sends a notification for this zone, it will be added again!'),$slave_master);