Checkmk Werk 11759: Fix broken "Discovery state" filter in customized view

ID: 11759 Title: Fix broken "Discovery state" filter in customized view Component: Multisite Level: 1 Class: Bug fix Version: 2.1.0i1 After editing a view containing the filter "Discovery state", subsequent edits of the view created the crash report: "TypeError (Only str and unicode values are allowed, got <class 'bool'>)".