Check_MK Werk 2670: Fix problem that no site is configured when user has deleted only site

ID: 2670 Title: Fix problem that no site is configured when user has deleted only site Component: Multisite Level: 2 Class: Bug Fix Version: 1.2.7i4 This problem was introduced by dropping the "single site" mode internally totally in version 1.2.7i3 and treating a single site setup automatically as multi site setup with just one site. The problem occurred when you had <tt>sites = {}</tt> in your configuration (instead of having no <tt>sites = </tt> at all).