fix _BIND_MODE_DIRECT _BIND_MODE_GROUP interactions


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@13766 e27351fd-9f3e-4f54-a53b-843176b1656c
merge in trunk through r13765


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@13767 e27351fd-9f3e-4f54-a53b-843176b1656c