Check_MK Werk 2647: Fix crash of CMC in case of duplicate host

ID: 2647 Title: Fix crash of CMC in case of duplicate host Component: Core & Setup Level: 1 Class: Bug Fix Version: 1.2.7i3 In certain situtations when you have a non-valid configuration (e.g. a duplicate host) than the Check_MK Micro Core would not be able to start correctly due to a problem in the handling of errors in the RRD creation helper. This has been fixed.