Check_MK Werk 2430: Fixed crash with availability queries when using nagios as core

ID: 2430 Title: Fixed crash with availability queries when using nagios as core Component: Core & Setup Level: 2 Class: Bug Fix Version: 1.2.7i3 The nagios core crashed when a query on the statehist table did return zero entries. This happened when a timewindow was queried where the hosts/services in question did not exist.