Checkmk Werk 13667: Fix label search for labels with same key

ID: 13667 Title: Fix label search for labels with same key Component: Multisite Level: 1 Class: Bug fix Version: 2.1.0i1 If you used different labels with the same key, e.g. "foo:bar" and "foo:baz", the label search with filters in views and dropdown input fields in rules only showed one label, ignoring all other labels with the same key.