OAK-781: Clarify / fix effects of MISSING_NODE as base state of NodeBuilder
(@Ignored) test case demonstrating failing assertion when an intermediate node of a builder hierarchy is based on a node existing node state

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1468861 13f79535-47bb-0310-9956-ffa450edef68