Checkmk Werk 13929: checkbox tag-group handling

ID: 13929 Title: checkbox tag-group handling Component: Core & setup Level: 1 Class: Bug fix Version: 2.2.0i1 In previous versions when a tag-group with only one choice (a checkbox) was set to a folder and subsequently removed on a host in that folder, the "show hosts" REST API call on that folder crashed with a 500 error (with the error: "tag_xxx can not be None"). This werk fixes this behaviour. Apache still needs to be restarted so newly created tag-groups come into effect on the REST API.