OAK-1941 - add test MAX update of _modified

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1631348 13f79535-47bb-0310-9956-ffa450edef68
OAK-1941 - add test MAX update of _modified (fix)

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1631353 13f79535-47bb-0310-9956-ffa450edef68